I.

We have considered the Aristotelian philosophy in relation to the great concrete interests of life, morals, politics, literature, and science. We have now to ask what it has to tell us about the deepest and gravest problems of any, the first principles of Being and Knowing, God and the soul, spirit and matter, metaphysics, psychology, and logic. We saw that very high claims were advanced on behalf of Aristotle in respect to his treatment of these topics; and had we begun with them, we should only have been following the usual example of his expositors. We have, however, preferred keeping them to the last, that our readers might acquire some familiarity with the Aristotelian method, by seeing it applied to subjects where the results were immediately intelligible, and could be tested by an appeal to the experience of twenty-two centuries. We know that there are some who will demur to this proceeding, who will say that Aristotle the metaphysician stands on quite different ground from Aristotle the man of science, because in the one capacity he had, and in the other capacity he had not, sufficient facts to warrant an authoritative conclusion. They will say, with Prof. St. George Mivart, that in accumulating natural knowledge men’s minds have become deadened to spiritual truth; or with Mr. Edwin Wallace, that the questions opened by Aristotle have not yet been closed, and that we may with advantage begin331 our study of them under his guidance. We, on the other hand, will endeavour to show that there is a unity of composition running through the Stagirite’s entire labours, that they everywhere manifest the same excellences and defects, which are those of an anatomising, critical, descriptive, classificatory genius; that his most important conclusions, however great their historical interest, are without any positive or even educational value for us, being almost entirely based on false physical assumptions; that his ontology and psychology are not what his admirers suppose them to be; and that his logic, though meriting our gratitude, is far too confused and incomplete to throw any light on the questions raised by modern thinkers.

Here, as elsewhere, we shall employ the genetic method of investigation. Aristotle’s writings do not, indeed, present that gradual development of ideas which makes the Platonic Dialogues so interesting. Still they exhibit traces of such a development, and the most important among them seems to have been compiled from notes taken by the philosopher before his conclusions were definitely reasoned out, or worked up into a consistent whole. It is this fragmentary collection which, from having been placed by some unknown editor after the Physics, has received a name still associated with every kind of speculation that cannot be tested by a direct or indirect appeal to the evidence of external sense.

Whether there exist any realities beyond what are revealed to us by this evidence, and what sensible evidence itself may be worth, were problems already actively canvassed in Aristotle’s time. His Metaphysics at once takes us into the thick of the debate. The first question of that age was, What are the causes and principles of things? On one side stood the materialists—the old Ionian physicists and their living representatives. They said that all things came from water or air or fire, or from a mixture of the four elements, or from the interaction of opposites, such as wet and dry, hot and cold.332 Aristotle, following in the track of his master, Plato, blames them for ignoring the incorporeal substances, by which he does not mean what would now be understood—feelings or states of consciousness, or even the spiritual substratum of consciousness—but rather the general qualities or assemblages of qualities which remain constant amid the fluctuations of sensible phenomena; considered, let us observe, not as subjective thoughts, but as objective realities. Another deficiency in the older physical theories is that they either ignore the efficient cause of motion altogether (like Thales), or assign causes not adequate to the purpose (like Empedocles); or when they hit on the true cause do not make the right use of it (like Anaxagoras). Lastly, they have omitted to study the final cause of a thing—the good for which it exists.

The teleology of Aristotle requires a word of explanation, which may appropriately find its place in the present connexion. In speaking of a purpose in Nature, he does not mean that natural productions subserve an end lying outside themselves; as if, to use Goethe’s illustration, the bark of cork-trees was intended to be made into stoppers for ginger-beer bottles; but that in every perfect thing the parts are interdependent, and exist for the sake of the whole to which they belong. Nor does he, like so many theologians, both ancient and modern, argue from the evidence of design in Nature to the operation of a designing intelligence outside her. Not believing in any creation at all apart from works of art, he could not believe in a creative intelligence other than that of man. He does, indeed, constantly speak of Nature as if she were a personal providence, continually exerting herself for the good of her creatures. But, on looking a little closer, we find that the agency in question is completely unconscious, and may be identified with the constitution of each particular thing, or rather of the type to which it belongs. We have said that Aristotle’s intellect was essentially descriptive, and we have here another illustration of its characteristic quality.333 The teleology which he parades with so much pomp adds nothing to our knowledge of causes, implies nothing that a positivist need not readily accept. It is a mere study of functions, an analysis of statical relations. Of course, if there were really any philosophers who said that the connexion between teeth and mastication was entirely accidental, the Aristotelian doctrine was a useful protest against such an absurdity; but when we have established a fixed connexion between organ and function, we are bound to explain the association in some more satisfactory manner than by reaffirming it in general terms, which is all that Aristotle ever does. Again, whatever may be the relative justification of teleology as a study of functions in the living body, we have no grounds for interpreting the phenomena of inorganic nature on an analogous principle. Some Greek philosophers were acute enough to perceive the distinction. While admitting that plants and animals showed traces of design, they held that the heavenly bodies arose spontaneously from the movements of a vortex or some such cause;222 just as certain religious savants of our own day reject the Darwinian theory while accepting the nebular hypothesis.223 But to Aristotle the unbroken regularity of the celestial movements, which to us is the best proof of their purely mechanical nature, was, on the contrary, a proof that they were produced and directed by an absolutely reasonable purpose; much more so indeed than terrestrial organisms, marked as these are by occasional deviations and imperfections; and he concludes that each of those movements must be directed towards the attainment of some correspondingly consummate end;224 while, again, in dealing with those precursors of Mr. Darwin, if such they can be called, who argued that the utility of an organ does not disprove its spontaneous origin, since only the creatures which, by a happy accident, came to possess it would survive—he334 answers that the constant reproduction of such organs is enough to vindicate them from being the work of chance;225 thus displaying his inability to distinguish between the two ideas of uniform causation and design.

As a result of the foregoing criticism, Aristotle distinguishes four different causes or principles by which all things are determined to be what they are—Matter, Form, Agent, and Purpose.226 If, for example, we take a saw, the matter is steel; the form, a toothed blade; the agent or cause of its assuming that shape, a smith; the purpose, to divide wood or stone. When we have enumerated these four principles, we have told everything that can be known about a saw. But Aristotle could not keep the last three separate; he gradually extended the definition of form until it absorbed, or became identified with, agent and purpose.227 It was what we should call the idea of function that facilitated the transition. If the very essence or nature of a saw implies use, activity, movement, how can we define it without telling its purpose? The toothed blade is only intelligible as a cutting, dividing instrument. Again, how came the saw into being? What shaped the steel into that particular form? We have said that it was the smith. But surely that is too vague. The smith is a man, and may be able to exercise other trades as well. Suppose him to be a musician, did he make the saw in that capacity? No; and here comes in a distinction which plays an immense part in Aristotle’s metaphysics, whence it has passed into our every-day speech. He does not make the saw qua musician but qua smith. He can, however, in the exercise of his trade as smith make many other tools—knives, axes, and so forth. Nevertheless, had he only learned to make saws it would be enough. Therefore, he does not make335 the saw qua axe-maker, he makes it qua saw-maker. Nor, again, does he make it with his whole mind and body, but only with just those thoughts and movements required to give the steel that particular shape. Now, what are these thoughts but the idea of a saw present in his mind and passing through his eyes and hands, till it fixes itself on the steel? The immaterial form of a saw creates the real saw which we use. Let us apply the preceding analogies to a natural object; for example, a man. What is the Form, the definition of a man? Not a being possessing a certain outward shape, for then a marble statue would be a man, which it is not; nor yet a certain assemblage of organs, for then a corpse would be a man, which, according to Aristotle, criticising Democritus, it is not; but a living, feeling, and reasoning being, the end of whose existence is to fulfil all the functions involved in this definition. So, also, the creative cause of a man is another man, who directly impresses the human form on the material supplied by the female organism. In the same way, every definite individual aggregate becomes what it is through the agency of another individual representing the same type in its perfect manifestation.228

The substantial forms of Aristotle, combining as they do the notion of a definition with that of a moving cause and a fulfilled purpose, are evidently derived from the Platonic Ideas; a reflection which at once leads us to consider the relation in which he stands to the spiritualism of Plato and to the mathematical idealism of the Neo-Pythagoreans. He agrees with them in thinking that general conceptions are the sole object of knowledge—the sole enduring reality in a world of change. He differs from them in maintaining that such conceptions have no existence apart from the particulars in which they reside. It has been questioned whether Aristotle ever really understood his master’s teaching on the subject. Among recent critics, M. Barthélemy Saint-Hilaire asserts,336 with considerable vehemence, that he did not. It is certain that in some respects Aristotle is not just to the Platonic theory, that he exaggerates its absurdities, ignores its developments, and occasionally brings charges against it which might be retorted with at least equal effect against his own philosophy. But on the most important point of all, whether Plato did or did not ascribe a separate existence to his Ideas, we could hardly believe a disciple of twenty years’ standing229 to be mistaken, even if the master had not left on record a decisive testimony to the affirmative side in his Parmenides, and one scarcely less decisive in his Timaeus.230 And so far as the controversy reduces itself to this particular issue, Aristotle is entirely right. His most powerful arguments are not, indeed, original, having been anticipated by Plato himself; but as they were left unanswered he had a perfect right to repeat them, and his dialectical skill was great enough to make him independent of their support. The extreme minuteness of his criticism is wearisome to us, who can hardly conceive how another opinion could ever have been held. Yet such was the fascination exercised by Plato’s idealism, that not only was it upheld with considerable acrimony by his immediate followers,231 but under one form or another it has been revived over and over again, in the long period which has elapsed since its first promulgation, and on every one of these occasions the arguments of Aristotle have been raised up again to meet it, each time with triumphant success. Ockham’s razor, Entia non sunt sine necessitate multiplicanda, is borrowed from the Metaphysics; Locke’s principal objection to innate ideas closely resembles the sarcastic observation in337 the last chapter of the Posterior Analytics, that, according to Plato’s theory, we must have some very wonderful knowledge of which we are not conscious.232 And the weapons with which Trendelenburg and others have waged war on Hegel are avowedly drawn from the Aristotelian arsenal.233

In his criticism on the ideal theory, Aristotle argues that it is unproved; that the consequences to which it leads would be rejected by the idealists themselves; that it involves a needless addition to the sum of existence; that it neither explains the origin of things nor helps us to understand them, while taking away from them their substantial reality; that the Ideas are merely sensible objects hypostasised, like the anthropomorphic divinities of primitive men; that, to speak of them as patterns, in whose likeness the world was created, is a mere idle metaphor; that, even assuming the existence of such patterns, each individual must be made in the likeness, not of one, but of many ideas—a human being, for instance, must be modelled after the ideal biped and the ideal animal, as well as after the ideal man; while many of the ideas themselves, although all are supposed to exist absolutely, must be dependent on other and simpler types; finally, that, assuming an idea for every abstract relation, there must be ideas to represent the relation between every sensible object and its prototype, others for the new relations thus introduced, and so on to infinity.

Aristotle’s objections to the Neo-Pythagorean theory of ideal numbers need not delay us here. They are partly a repetition of those brought against the Platonic doctrine in its338 original form, partly derived from the impossibility of identifying qualitative with quantitative differences.234

Such arguments manifestly tell not only against Platonism, but against every kind of transcendental realism, from the natural theology of Paley to the dogmatic agnosticism of Mr. Herbert Spencer. A modern Aristotle might say that the hypothesis of a creative first cause, personal or otherwise, logically involves the assumption of as many original specific energies as there are qualities to be accounted for, and thus gives us the unnecessary trouble of counting everything twice over; that every difficulty and contradiction from which the transcendental assumption is intended to free us, must, on analysis, reappear in the assumption itself—for example, the God who is to deliver us from evil must be himself conceived as the creator of evil; that the infinite and absolute can neither cause, nor be apprehended by, the finite and relative; that to separate from Nature all the forces required for its perpetuation, and relegate them to a sphere apart, is a false antithesis and a sterile abstraction; lastly, that causation, whether efficient or final, once begun, cannot stop; that if this world is not self-existing, nothing is; that the mutual adaptation of thoughts in a designing intelligence requires to be accounted for just like any other adaptation; that if the relative involves the absolute, so also does the relation between the two involve another absolute, and so on to infinity.

These are difficulties which will continue to perplex us until every shred of the old metaphysics has been thrown off. To that task Aristotle was not equal. He was profoundly influenced by the very theory against which he contended; and, at the risk of being paradoxical, we may even say that it assumed a greater importance in his system than had ever been attributed to it by Plato himself. To prove this, we must resume the thread of our exposition, and follow the339 Stagirite still further in his analysis of the fundamental reality with which the highest philosophy is concerned.
II.

Ever since the age of Parmenides and Heracleitus, Greek thought had been haunted by a pervading dualism which each system had in turn attempted to reconcile, with no better result than its reproduction under altered names. And speculation had latterly become still further perplexed by the question whether the antithetical couples supposed to divide all Nature between them could or could not be reduced to so many aspects of a single opposition. In the last chapter but one we showed that there were four such competing pairs—Being and Not-Being, the One and the Many, the Same and the Other, Rest and Motion. Plato employed his very subtlest dialectic in tracing out their connexions, readjusting their relationships, and diminishing the total number of terms which they involved. In what was probably his last great speculative effort, the Timaeus, he seems to have selected Sameness and Difference as the couple best adapted to bear the heaviest strain of thought. There is some reason for believing that in his spoken lectures he followed the Pythagorean system more closely, giving the preference to the One and the Many; or he may have employed the two expressions indifferently. The former would sooner commend itself to a dialectician, the latter to a mathematician. Aristotle was both, but he was before all things a naturalist. As such, the antithesis of Being and Not-Being, to which Plato attached little or no value, suited him best. Accordingly, he proceeds to work it out with a clearness before unknown in Greek philosophy. The first and surest of all principles, he declares, is, that a thing cannot both be and not be, in the same sense of the words, and furthermore that it must either be or not be. Subsequent340 logicians prefixed to these axioms another, declaring that whatever is is. The three together are known as the laws of Identity, Contradiction, and Excluded Middle. By all, except Hegelians, they are recognised as the highest laws of thought; and even Hegel was indebted to them, through Fichte, for the ground-plan of his entire system.235

The whole meaning and value of such excessively abstract propositions must lie in their application to the problems which they are employed to solve. Aristotle made at once too much and too little of his. Too much—for he employed them to refute doctrines not really involving any logical inconsistency—the theory of Heracleitus, that everything is in motion; the theory of Anaxagoras, that everything was originally confused together; the theory of Protagoras, that man is the measure of all things. Too little—for he admitted a sphere of possibilities where logical definition did not apply, and where subjects simultaneously possessed the capacity of taking on one or other of two contradictory attributes.

Nor is this all. After sharply distinguishing what is from what is not, and refusing to admit any intermediary between them, Aristotle proceeds to discover such an intermediary in the shape of what he calls Accidental Predication.236 An accident is an attribute not necessarily or usually inhering in its subject—in other words, a co-existence not dependent on causation. Aristotle could never distinguish between the two notions of cause and kind, nor yet between interferences with the action of some particular cause and exceptions to the law of causation in general; and so he could not frame an intelligible theory of chance. Some propositions, he tells us, are necessarily true, others are only generally true; and it is the exceptions to the latter which constitute accident; as, for instance, when a cold day happens to come in the middle341 of summer. So also a man is necessarily an animal, but only exceptionally white. Such distinctions are not uninteresting, for they prove with what difficulties the idea of invariable sequence had to contend before even the highest intellects could grasp it. There was a constant liability to confound the order of succession with the order of co-existence, the order of our sensations with the order of objective existence, and the subjection of human actions to any fixed order, with the impossibility of deliberation and choice. The earlier Greek thinkers had proclaimed that all things existed by necessity; but with their purely geometrical or historical point of view, they entirely ignored the more complex questions raised by theories about classification, logical attribution, and moral responsibility. And the modifications introduced by Epicurus, into the old physics, show us how unanswerable Aristotle’s reasonings seemed to some of his ablest successors.

Absolute being is next distinguished from truth, which, we are told, has no objective existence237—a remarkable declaration, which throws much light on other parts of the Aristotelian system, and to which we shall subsequently return.238

After explaining at considerable length what Being is not, Aristotle now proceeds to ascertain what it is. He tells us that just as all number qua number must be either odd or even, so all Being qua Being must have certain universal attributes. These he sets himself to discover. When Descartes long afterwards entered on a somewhat similar inquiry, he fell back on the facts of his own individual consciousness. Aristotle, on the contrary, appeals to the common consciousness of mankind as embodied in ordinary language. In how many senses do we say that a thing is? The first answer is contained in his famous Ten Categories.239 These342 are not what some have supposed them to be, summa genera of existence, but summa genera of predication. In other words, they are not a classification of things, but of the information which it is possible to receive about a single thing, more especially about the richest and most concrete thing known to us—a human being. If we want to find out all about a thing we ask, What is it? Of what sort? How large? To what does it belong? Where and when can we find it? What does it do? What happens to it? And if the object of our investigations be a living thing, we may add, What are its habits and dispositions? The question has been raised, how Aristotle came to think of these ten particular categories, and a wonderful amount of rubbish has been written on the subject, while apparently no scholar could see what was staring him in the face all the time, that Aristotle got them by collecting all the simple forms of interrogation supplied by the Greek language,240 and writing out their most general expressions.

Having obtained his categories, Aristotle proceeds to mark off the first from the other nine. The subject or substance named in answer to the question, What is it? can exist without having any quality, size, and so forth predicated of it; but they cannot exist without it. Logically, they cannot be defined without telling what they are; really they cannot be conceived without something not themselves in343 which they inhere. They are like the tail of a kite, giving greater conspicuousness and buoyancy to the body, but entirely dependent on it for support. What our philosopher fails to perceive is, that the dependence is reciprocal, that substance can no more be conceived without attributes than attributes without substance; or rather that substance, like all other categories, can be resolved into Relation.241

Meanwhile, he had a logical machine ready to hand, which could be used with terrible effect against the Platonic Ideas. Any of these—and there were a great number—that could be brought under one of the last nine categories were at once deprived of all claim to independent existence. Take Equality, for instance. It cannot be discovered outside quantity, and quantity is always predicated of a substance. And the same is true of number, to the utter destruction of the Neo-Pythagorean theory which gave it a separate existence. Moreover, the categories served not only to generalise and combine, but also to specificate and divide. The idea of motion occurs in three of them; in quantity, where it means increase or diminution; in quality, where it means alteration, as from hot to cold, or vice versa; and in place, implying transport from one point to another. The Idea of Good, which stands at the very summit of Plato’s system, may be traced through all ten categories.242 Thus, the supposed unity and simplicity of such conceptions was shown to be an illusion. Platonism was, in truth, so inconsistent with the notions embodied in common language, that it could not but be condemned by a logic based on those notions.

Aristotle next takes the Idea of Substance and subjects it to a fresh analysis.243 Of all things none seem to possess so evident an existence as the bodies about us—plants and animals, the four elements, and the stars. But each of these344 has already been shown to consist of Form and Matter. A statue, for instance, is a lump of bronze shaped into the figure of a man. Of these two constituents, Matter seems at first sight to possess the greater reality. The same line of thought which led Aristotle to place substance before the other categories now threatens to drive him back into materialism. This he dreaded, not on sentimental or religious grounds, but because he conceived it to be the negation of knowledge. He first shows that Matter cannot be the real substance to which individuals owe their determinate existence, since it is merely the unknown residuum left behind when every predicate, common to them with others, has been stripped off. Substance, then, must be either Form alone or Form combined with Matter. Form, in its completest sense, is equivalent to the essential definition of a thing—the collection of attributes together constituting its essence or conception. To know the definition is to know the thing defined. The way to define is to begin with the most general notion, and proceed by adding one specific difference after another, until we reach the most particular and concrete expression. The union of this last with a certain portion of Matter gives us the individual Socrates or Callias. There are no real entities (as the Platonists pretend) corresponding to the successive stages of generalisation, biped, animal, and so forth, any more than there are self-existing quantities, qualities, and relations. Thus the problem has been driven into narrower and narrower limits, until at last we are left with the infim? species and the individuals contained under them. It remains to discover in what relation these stand to one another. The answer is unsatisfactory. We are told that there is no definition of individuals, and also that the definition is identical with the individual.244 Such, indeed, is the conclusion necessarily resulting from Aristotle’s repeated declarations that all knowledge is of345 definitions, that all knowledge is of something really existing, and that nothing really exists but individual things. Nevertheless, against these we have to set equally strong declarations to the effect that knowledge is of something general, not of the perishing individuals which may pass out of existence at any moment. The truth is, that we are here, as Zeller has shown,245 in presence of an insoluble contradiction, and we must try to explain, not how Aristotle reconciled it with itself, for that was impossible, but how he reconciled himself to it.

His analysis of individuality was the first step in this direction. We have seen that he treats definition as a process of gradual specification, beginning with the most general notions, and working down by successive differentiations to the most particular. Now, the completed conception is itself the integration of all these differences, the bond of union holding them together. Turning to an antithetical order of ideas, to the material substance of which bodies are composed, and its various transformations, we find him working out the same vein of thought. According to the Aristotelian chemistry, an ultimate indeterminate unknowable something clothes itself with one or other of the opposing attributes, dry and moist, hot and cold; and when two of these are combined, manifests itself to our senses as one of the four elements. The elements combine in a particular manner to form homogeneous animal tissues, and these again are united into heterogeneous organs, which together constitute the living body. Here, then, we have two analogous series of specifications—one conceptual and leading down from the abstract to the concrete, the other physical, and leading up from the vague, the simple, and the homogeneous, to the definite, the complex, and the heterogeneous. Aristotle embraces both processes under a single comprehensive generalisation. He describes each of them as the continuous conversion of a346 possibility into an actuality. For the sake of greater clearness, let us take the liberty of substituting modern scientific terms for his cumbrous and obsolete classifications. We shall then say that the general notion, living thing, contains under it the two less general notions—plant and animal. If we only know of any given object that it has life, there is implied the possibility of its being either the one or the other, but not both together. On determining it to be (say) an animal, we actualise one of the possibilities. But the actualisation is only relative, and immediately becomes the possibility of being either a vertebrate or an invertebrate animal. The actuality vertebrate becomes the possibility of viviparous or oviparous, and so on through successive differentiations until we come (say) to a man. Now let us begin at the material end. Here are a mass of molecules, which, in their actual state are only carbon, nitrogen, and so forth. But they are potential starch, gluten, water, or any other article of food that might be named; for under favourable conditions they will combine to form it. Once actualised as such, they are possible blood-cells; these are possible tissues; these, again, possible organs, and lastly we come to the consensus of vital functions, which is a man. What the raw material is to the finished product, that are the parts to the entire organism, the elements to the compound, the genus to the species, and such in its very widest sense is potency to realisation, δ?ναμι? to ?ντελ?χεια, throughout the universe of growth and decay.246

It will be observed that, so far, this famous theory does not add one single jot to our knowledge. Under the guise of an explanation, it is a description of the very facts needing to be explained. We did not want an Aristotle to tell us that before a thing exists it must be possible. We want to know how it is possible, what are the real conditions of its existence, and why they combine at a particular moment to347 produce it. The Atomists showed in what direction the solution should be sought, and all subsequent progress has been due to a development of their method. Future ages will perhaps consider our own continued distinction between force and motion as a survival of the Peripatetic philosophy. Just as sensible aggregates of matter arise not out of potential matter, but out of matter in an extremely fine state of diffusion, so also sensible motion will be universally traced back, not to potential motion, which is all that force means, but to molecular or ethereal vibrations, like those known to constitute heat and light.

We have said, in comparing him with his predecessors, that the Stagirite unrolled Greek thought from a solid into a continuous surface. We have now to add that he gave his surface the false appearance of a solid by the use of shadows, and of a?rial perspective. In other words, he made the indication of his own ignorance and confusion do duty for depth and distance. For to say that a thing is developed out of its possibility, merely means that it is developed out of something, the nature of which we do not know. And to speak about such possibilities as imperfect existences, or matter, or whatever else Aristotle may be pleased to call them, is simply constructing the universe, not out of our ideas, but out of our absolute want of ideas.

We have seen how, for the antithesis between Form and Matter, was substituted the wider antithesis between Actuality and Possibility. Even in this latter the opposition is more apparent than real. A permanent possibility is only intelligible through the idea of its realisation, and sooner or later is certain to be realised. Aristotle still further bridges over the interval between them by a new conception—that of motion. Motion, he tells us, is the process of realisation, the transformation of power into act. Nearly the whole of his Physics is occupied with an enquiry into its nature and origin. As first conceived, it is equivalent to what we call change rather than348 to mechanical movement. The table of categories supplies an exhaustive enumeration of its varieties. These are, as we have already mentioned, alteration of quality or transformation, increase or decrease of quantity, equivalent to growth and decay, and transport from place to place. Sometimes a fourth variety is added, derived from the first category, substance. He calls it generation and destruction, the coming into existence or passing out of it again. A careful analysis shows that motion in space is the primordial change on which all others depend for their accomplishment. To account for it is the most vitally important problem in philosophy.
III.

Before entering on the chain of reasoning which led Aristotle to postulate the existence of a personal First Cause, we must explain the difference between his scientific standpoint, and that which is now accepted by all educated minds. To him the eternity not only of Matter, but also of what he called Form,—that is to say, the collection of attributes giving definiteness to natural aggregates, more especially those known as organic species—was an axiomatic certainty. Every type, capable of self-propagation, that could exist at all, had existed, and would continue to exist for ever. For this, no explanation beyond the generative power of Nature was required. But when he had to account for the machinery by which the perpetual alternation of birth and death below, and the changeless revolutions of the celestial spheres above the moon were preserved, difficulties arose. He had reduced every other change to transport through space; and with regard to this his conceptions were entirely mistaken. He believed that moving matter tended to stop unless it was sustained by some external force; and whatever their advantages over him in other respects, we cannot say that the Atomists were in a position to correct him here: for their349 theory, that every particle of matter gravitated downward through infinite space, was quite incompatible with the latest astronomical discoveries. Aristotle triumphantly showed that the tendency of heavy bodies was not to move indefinitely downwards in parallel lines, but to move in converging lines to the centre of the earth, which he, in common with most Greek astronomers, supposed to be also the centre of the universe; and seeing light bodies move up, he credited them with an equal and opposite tendency to the circumference of the universe, which, like Parmenides and Plato, he believed to be of finite extent. Thus each kind of matter has its appropriate place, motion to which ends in rest, while motion away from it, being constrained, cannot last. Accordingly, the constant periodicity of terrestrial phenomena necessitates as constant a transformation of dry and wet, and of hot and cold bodies into one another. This is explained with perfect accuracy by the diurnal and annual revolutions of the sun. Here, however, we are introduced to a new kind of motion, which, instead of being rectilinear and finite, is circular and eternal. To account for it, Aristotle assumes a fifth element entirely different in character from the four terrestrial elements. Unlike them, it is absolutely simple, and has a correspondingly simple mode of motion, which, as our philosopher erroneously supposes, can be no other than circular rotation.

Out of this eternal unchanging divine substance, which he calls aether, are formed the heavenly bodies and the transparent spheres containing them. But there is something beyond it of an even higher and purer nature. Aristotle proves, with great subtlety, from his fundamental assumptions, that the movement of an extended substance cannot be self-caused. He also proves that motion must be absolutely continuous and without a beginning. We have, therefore, no choice but to accept the existence of an unextended, immaterial, eternal, and infinite Power on which the whole cosmos depends.

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So much only is established in the Physics. Further particulars are given in the twelfth book of the Metaphysics. There we learn that, all movement being from possibility to actuality, the source of movement must be a completely realised actuality—pure form without any admixture of matter. But the highest form known to us in the ascending scale of organic life is the human soul, and the highest function of soul is reason. Reason then must be that which moves without being moved itself, drawing all things upwards and onwards by the love which its perfection inspires. The eternal, infinite, absolute actuality existing beyond the outermost starry sphere is God. Aristotle describes God as the thought which thinks itself and finds in the simple act of self-consciousness an everlasting happiness, wonderful if it always equals the best moments of our mortal life, more wonderful still if it surpasses them. There is only one supreme God, for plurality is due to an admixture of matter, and He is pure form. The rule of many is not good, as Homer says. Let there be one Lord.

Such are the closing words of what was possibly Aristotle’s last work, the clear confession of his monotheistic creed. A monotheistic creed, we have said, but one so unlike all other religions, that its nature has been continually misunderstood. While some have found in it a theology like that of the Jews or of Plato or of modern Europe, others have resolved it into a vague pantheism. Among the latter we are surprised to find Sir A. Grant, a writer to whom the Aristotelian texts must be perfectly familiar both in spirit and in letter. Yet nothing can possibly be more clear and emphatic than the declarations they contain. Pantheism identifies God with the world; Aristotle separates them as pure form from form more or less alloyed with matter. Pantheism denies personality to God; Aristotle gives him unity, spirituality, self-consciousness, and happiness. If these qualities do not collectively involve personality, we should like to know what does. Need we351 remind the accomplished editor of the Nicomachean Ethics how great a place is given in that work to human self-consciousness, to waking active thought as distinguished from mere slumbering faculties or unrealised possibilities of action? And what Aristotle regarded as essential to human perfection, he would regard as still more essential to divine perfection. Finally, the God of pantheism is a general idea; the God of Aristotle is an individual. Sir A. Grant says that he (or it) is the idea of Good.247 We doubt very much whether there is a single passage in the Metaphysics to sanction such an expression. Did it occur, however, that would be no warrant for approximating the Aristotelian to the Platonic theology, in presence of such a distinct declaration as that the First Mover is both conceptually and numerically one,248 coming after repeated repudiations of the Platonic attempt to isolate ideas from the particulars in which they are immersed. Then Sir A. Grant goes on to speak of the desire felt by Nature for God as being itself God,249 and therefore involving a belief in pantheism. Such a notion is not generally called pantheism, but hylozoism, the attribution of life to matter. We have no desire, however, to quarrel about words. The philosopher who believes in the existence of a vague consciousness, a spiritual effort towards something higher diffused through nature, may, if you will, be called a pantheist, but not unless this be the only divinity he recognises. The term is altogether misleading when applied to one who also proclaims the existence of something in his opinion far higher, better and more real—a living God, who transcends Nature, and is independent of her, although she is not independent of him.

We must also observe that the parallel drawn by Sir A. Grant between the theology of Aristotle and that of John Stuart Mill is singularly unfortunate. It is in the first place incorrect to say that Mill represented God as benevolent but352 not omnipotent. He only suggested the idea as less inconsistent with facts than other forms of theism.250 In the next place, Aristotle’s God was almost exactly the reverse of this. He possesses infinite power, but no benevolence at all. He has nothing to do with the internal arrangements of the world, either as creator or as providence. He is, in fact, an egoist of the most transcendent kind, who does nothing but think about himself and his own perfections. Nothing could be more characteristic of the unpractical Aristotelian philosophy; nothing more repugnant to the eager English reformer, the pupil of Bentham and of Plato. And, thirdly, Sir A. Grant takes what is not the God of Aristotle’s system at all, but a mere abstraction, the immanent reason of Nature, the Form which can never quite conquer Matter, and places it on the same line with a God who, however hypothetical, is nothing if not a person distinct from the world; while, as if to bewilder the unfortunate ‘English reader’ still further, he adds, in the very next sentence, that ‘the great defect in Aristotle’s conception of God is’ the denial ‘that God can be a moral Being.’251

The words last quoted, which in a Christian sense are true enough, lead us over to the contrasting view of Aristotle’s theology, to the false theory of it held by critics like Prof. St. George Mivart. The Stagirite agrees with Catholic theism in accepting a personal God, and he agrees with the First Article of the English Church, though not with the Pentateuch, in saying that God is without parts or passions; but there his agreement ceases. Excluding such a thing as divine interference with nature, his theology of course excludes the possibility of revelation, inspiration, miracles, and grace. Nor is this a mere omission; it is a necessity of the system. If there can353 be no existence without time, no time without motion, no motion without unrealised desire, no desire without an ideal, no ideal but eternally self-thinking thought—then it logically follows that God, in the sense of such a thought, must not interest himself in the affairs of men. Again, Aristotelianism equally excludes the arguments by which modern theologians have sought to prove the existence of God. Here also the system is true to its contemporaneous, statical, superficial character. The First Mover is not separated from us by a chain of causes extending through past ages, but by an intervening breadth of space and the wheels within wheels of a cosmic machine. Aristotle had no difficulty in conceiving what some have since declared to be inconceivable, a series of antecedents without any beginning in time; it was rather the beginning of such a series that he could not make intelligible to himself. Nor, as we have seen, did he think that the adaptation in living organisms of each part to every other required an external explanation. Far less did it occur to him that the production of impressions on our senses was due to the agency of a supernatural power. It is absolutely certain that he would have rejected the Cartesian argument, according to which a perfect being must exist if it be only conceivable—existence being necessarily involved in the idea of perfection.252 Finally, not recognising such a faculty as conscience, he would not have admitted it to be the voice of God speaking in the soul.

On the other hand, Aristotle’s own theistic arguments cannot stand for a moment in the face of modern science. We know by the law of inertia that it is not the continuance, but the arrest or the beginning of motion which requires to be accounted for. We know by the Copernican system that there is no solid sidereal sphere governing the revolutions of all Nature. And we know by the Newtonian physics that354 gravitation is not dependent on fixed points in space for its operation. The Philosophy of the Philosopher Aristotle is as inconsistent with the demonstrations of modern astronomy as it is with the faith of mediaeval Catholicism.

It remains to be seen whether the system which we are examining is consistent with itself. It is not. The Prime Mover, being unextended, cannot be located outside the sidereal sphere; nor can he be brought into immediate contact with it more than with any other part of the cosmos. If the aether has a motion proper to itself, then no spiritual agency is required to keep it in perpetual rotation. If the crystalline spheres fit accurately together, as they must, to avoid leaving a vacuum anywhere, there can be no friction, no production of heat, and consequently no effect produced on the sublunary sphere. Finally, no rotatory or other movement can, taken alone, have any conceivable connexion with the realisation of a possibility, in the sense of progress from a lower to a higher state of being. It is merely the perpetual exchange of one indifferent position for another.

We have now to consider what were the speculative motives that led Aristotle to overlook these contradictions, and to find rest in a theory even less satisfactory than the earlier systems which he is always attacking with relentless animosity. The first motive, we believe, was the train of reasoning, already laid before the reader, by which universal essences, the objects of knowledge, gradually came to be identified with particular objects, the sole existing realities. For the arguments against such an identification, as put forward by our philosopher himself, still remained unanswered. The individuals comprising a species were still too transient for certainty and too numerous for comprehension. But when for the antithesis between Form and Matter was substituted the antithesis between Actuality and Possibility, two modes of evasion presented themselves. The first was to distinguish between actual knowledge and potential knowledge.355 The former corresponded to existing particulars, the latter to general ideas.253 This, however, besides breaking up the unity of knowledge, was inconsistent with the whole tenor of Aristotle’s previous teaching. What can be more actual than demonstration, and how can there be any demonstration of transient particulars? The other mode of reconciliation was perhaps suggested by the need of an external cause to raise Possibility into Actuality. Such a cause might be conceived with all the advantages and without the drawbacks of a Platonic Idea. It would be at once the moving agent and the model of perfection; it could reconcile the general and the particular by the simple fact of being eternal in time, comprehensive in space, and unique in kind. Aristotle found such a cause, or rather a whole series of such causes, in the celestial spheres. In his system, these bear just the same relation to terrestrial phenomena that Plato’s Ideas bear to the world of sense. They are, in fact, the Ideas made sensible and superficial, placed alongside of, instead of beneath or behind, the transient particulars which they irradiate and sustain.

The analogy may be carried even farther. If Plato regarded the things of sense as not merely a veil, but an imperfect imitation of the only true realities; so also did Aristotle represent the sublunary elements as copying the disposition and activities of the ethereal spheres. They too have their concentric arrangements—first fire, then air, then water, and lastly earth in the centre; while their perpetual transformation into one another presents an image in time of the spatial rotation which those sublime beings perform. And although we think that Sir A. Grant is quite mistaken in identifying Aristotle’s Supreme Mind with the Idea of Good, there can be no doubt of its having been suggested by that Idea. It is, in fact, the translation of Plato’s abstraction into concrete reality, and the completion of a process which Plato356 had himself begun. From another point of view we may say that both master and disciple were working, each in his own way, at the solution of a problem which entirely dominates Greek philosophy from Empedocles on—the reconciliation of Parmenides and Heracleitus, Being and Becoming, the eternal and the changeful, the one and the many. Aristotle adopts the superficial, external method of placing the two principles side by side in space; and for a long time the world accepted his solution for the same reason that had commended it to his own acceptance, its apparent agreement with popular tradition and with the facts of experience. It must be confessed, however, that here also he was following the lines laid down by Plato. The Timaeus and the Laws are marked by a similar tendency to substitute astronomy for dialectics, to study the celestial movements with religious veneration, to rebuild on a scientific basis that ancient star-worship which, even among the Greeks, enjoyed a much higher authority and prestige than the humanised mythology of the poets. But for Christianity this star-worship would probably have become the official faith of the Roman world. As it is, Dante’s great poem presents us with a singular compromise between the two creeds. The crystalline spheres are retained, only they have become the abode of glorified spirits instead of being the embodiment of eternal gods. We often hear it said that the Copernican system was rejected as offensive to human pride, because it removed the earth from the centre of the universe. This is a profound mistake. Its offence was to degrade the heavenly bodies by assimilating them to the earth.254 Among several planets, all revolving round the sun, there could not be any marked qualitative difference. In the theological sense there was no longer any heaven; and with the disappearance of the solid357 sidereal sphere there was no longer any necessity for a Prime Mover.

There is, perhaps, no passage in Aristotle’s writings—there is certainly none in his scientific writings—more eloquent than that which describes the glory of his imaginary heavens. The following translation may give some faint idea of its solemnity and splendour:—

    We believe, then, that the whole heaven is one and everlasting, without beginning or end through all eternity, but holding infinite time within its orb; not, as some say, created or capable of being destroyed. We believe it on account of the grounds already stated, and also on account of the consequences resulting from a different hypothesis. For, it must add great weight to our assurance of its immortality and everlasting duration that this opinion may, while the contrary opinion cannot possibly, be true. Wherefore, we may trust the traditions of old time, and especially of our own race, when they tell us that there is something deathless and divine about the things which, although moving, have a movement that is not bounded, but is itself the universal bound, a perfect circle enclosing in its revolutions the imperfect motions that are subject to restraint and arrest; while this, being without beginning or end or rest through infinite time, is the one from which all others originate, and into which they disappear. That heaven which antiquity assigned to the gods as an immortal abode, is shown by the present argument to be uncreated and indestructible, exempt alike from mortal weakness and from the weariness of subjection to a force acting in opposition to its natural inclination; for in proportion to its everlasting continuance such a compulsion would be laborious, and unparticipant in the highest perfection of design. We must not, then, believe with the old mythologists that an Atlas is needed to uphold it; for they, like some in more recent times, fancied that the heavens were made of heavy earthy matter, and so fabled an animated necessity for their support; nor yet that, as Empedocles says, they will last only so long as their own proper momentum is exceeded by the whirling motion of which they partake.255 Nor, again, is it likely that their everlasting revolution can be kept up by the exercise of a conscious will;358 for no soul could lead a happy and blessed existence that was engaged in such a task, necessitating, as it would, an unceasing struggle with their native tendency to move in a different direction, without even the mental relaxation and bodily rest which mortals gain by sleep, but doomed to the eternal torment of an Ixion’s wheel. Our explanation, on the other hand, is, as we say, not only more consistent with the eternity of the heavens, but also can alone be reconciled with the acknowledged vaticinations of religious faith.256

It will be seen from the foregoing passage how strong a hold the old Greek notion of an encircling limit had on the mind of Aristotle, and how he transformed it back from the high intellectual significance given to it by Plato into its original sense of a mere space-enclosing figure. And it will also be seen how he credits his spheres with a full measure of that moving power which, according to his rather unfair criticism, the Platonic Ideas did not possess. His astronomy also supplied him with that series of graduated transitions between two extremes in which Greek thought so much delighted. The heavenly bodies mediate between God and the earth; partly active and partly passive, they both receive and communicate the moving creative impulse. The four terrestrial elements are moved in the various categories of substance, quantity, quality, and place; the aether moves in place only. God remains ‘without variableness or shadow of a change.’ Finally, by its absolute simplicity and purity, the aether mediates between the coarse matter perceived by our senses and the absolutely immaterial Nous, and is itself supposed to be pervaded by a similar gradation of fineness from top to bottom. Furthermore, the upper fire, which must not be confounded with flame, furnishes a connecting link between the aether and the other elements, being related to them as Form to Matter, or as agent to patient; and, when the elements are decomposed into their constituent qualities, hot and cold occupy a similar position with regard to wet and dry.

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IV.

In mastering Aristotle’s cosmology, we have gained the key to his entire method of systematisation. Henceforth, the Stagirite has no secrets from us. Where we were formerly content to show that he erred, we can now show why he erred; by generalising his principles of arrangement, we can exhibit them still more clearly in their conflict with modern thought. The method, then, pursued by Aristotle is to divide his subject into two more or less unequal masses, one of which is supposed to be governed by necessary principles, admitting of certain demonstration; while the other is irregular, and can only be studied according to the rules of probable evidence. The parts of the one are homogeneous and concentrically disposed, the movements of each being controlled by that immediately outside and above it. The parts of the other are heterogeneous and distributed among a number of antithetical pairs, between whose members there is, or ought to be, a general equilibrium preserved, the whole system having a common centre which either oscillates from one extreme to another, or holds the balance between them. The second system is enclosed within the first, and is altogether dependent on it for the impulses determining its processes of metamorphosis and equilibration. Where the internal adjustments of a system to itself or of one system to the other are not consciously made, Aristotle calls them Nature. They are always adapted to secure its everlasting continuance either in an individual or a specific form. Actuality belongs more particularly to the first sphere, and possibility to the second, but both are, to a certain extent, represented in each.

We have already seen how this fundamental division is applied to the universe as a whole. But our philosopher is not content with classifying the phenomena as he finds360 them; he attempts to demonstrate the necessity of their dual existence; and in so doing is guilty of something very like a vicious circle. For, after proving from the terrestrial movements that there must be an eternal movement to keep them going, he now assumes the revolving aether, and argues that there must be a motionless solid centre for it to revolve round, although a geometrical axis would have served the purpose equally well. By a still more palpable fallacy, he proceeds to show that a body whose tendency is towards the centre, must, in the nature of things, be opposed by another body whose tendency is towards the circumference. In order to fill up the interval created by this opposition, two intermediate bodies are required, and thus we get the four elements—earth, water, air, and fire. These, again, are resolved into the antithetical couples, dry and wet, hot and cold, the possible combinations of which, by twos, give us the four elements once more. Earth is dry and cold, water cold and wet, air wet and hot, fire hot and dry; each adjacent pair having a quality in common, and each element being characterized by the excess of a particular quality; earth is especially dry, water cold, air wet, and fire hot. The common centre of each antithesis is what Aristotle calls the First Matter, the mere abstract unformed possibility of existence. This matter always combines two qualities, and has the power of oscillating from one quality to another, but it cannot, as a rule, simultaneously exchange both for their opposites. Earth may pass into water, exchanging dry for wet, but not so readily into air, which would necessitate a double exchange at the same moment.

Those who will may see in all this an anticipation of chemical substitution and double decomposition. We can assure them that it will be by no means the most absurd parallel discovered between ancient and modern ideas. It is possible, however, to trace a more real connexion between the Aristotelian physics and mediaeval thought. We do not of361 course mean the scholastic philosophy, for there never was the slightest doubt as to its derivation; we allude to the alchemy and astrology which did duty for positive science during so many centuries, and even overlapped it down to the time of Newton, himself an ardent alchemist. The superstitions of astrology originated independently of the peripatetic system, and probably long before it, but they were likely to be encouraged by it instead of being repressed, as they would have been by a less anthropomorphic philosophy. Aristotle himself, as we have seen, limited the action of the heavens on the sublunary sphere to their heating power; but, by crediting them with an immortal reason and the pursuit of ends unknown to us, he opened a wide field for conjecture as to what those ends were, and how they could be ascertained. That the stars and planets were always thinking and acting, but never about our affairs, was not a notion likely to be permanently accepted. Neither was it easy to believe that their various configurations, movements, and names (the last probably revealed by themselves) were entirely without significance. From such considerations to the casting of horoscopes is not a far remove. The Aristotelian chemistry would still more readily lend itself to the purposes of alchemy. If Nature is one vast process of transmutation, then particular bodies, such as the metals, not only may, but must be convertible into one another. And even those who rejected Aristotle’s logic with scorn still clung to his natural philosophy when it flattered their hopes of gain. Bacon kept the theory of substantial forms. His originality consisted in looking for a method by which any form, or assemblage of forms might be superinduced at pleasure on the underlying matter. The real development of knowledge pursued a far different course. The great discoverers of the sixteenth and seventeenth centuries achieved their success by absolutely reversing the method of Aristotle, by bringing into fruitful contact principles which he had condemned to barren isolation.362 They carried terrestrial physics into the heavens; they brought down the absoluteness and eternity of celestial law to earth; they showed that Aristotle’s antithetical qualities were merely quantitative distinctions. These they resolved into modes of motion; and they also resolved all motions into one, which was both rectilinear and perpetual. But they and their successors put an end to all dreams of transmutation, when they showed by another synthesis that all matter, at least within the limits of our experience, has the changeless consistency once attributed exclusively to the stellar spheres.

When Aristotle passes from the whole cosmos to the philosophy of life, his method of systematic division is less distinctly illustrated, but still it may be traced. The fundamental separation is between body and soul. The latter has a wider meaning than what we associate with it at present. It covers the psychic functions and the whole life of the organism, which, again, is not what we mean by life. For life with us is both individual and collective; it resides in each speck of protoplasm, and also in the consensus of the whole organism. With Aristotle it is more exclusively a central principle, the final cause of the organism, the power which holds it together, and by which it was originally shaped. Biology begins by determining the idea of the whole, and then considers the means by which it is realised. The psychic functions are arranged according to a system of teleological subordination. The lower precedes the higher in time, but is logically necessitated by it. Thus nutrition, or the vegetative life in general, must be studied in close connexion with sensation and impulse, or animal life; and this, again, with thought or pure reasoning. On the other hand, anatomy and physiology are considered from a purely chemical and mechanical point of view. A vital purpose is, indeed, assigned to every organ, but with no more reference to its specifically vital properties than if it formed part of a steam engine. Here, as always with Aristotle, the idea of moderation determines the point of view363 whence the inferior or material system is to be studied. Organic tissue is made up of the four elemental principles—hot, cold, wet, and dry—mixed together in proper proportions; and the object of organic function is to maintain them in due equilibrium, an end effected by the regulating power of the soul, which, accordingly, has its seat in the heart or centre of the body. It has been already shown how, in endeavouring to work out this chimerical theory, Aristotle went much further astray from the truth than sundry other Greek physiologists less biassed by the requirements of a symmetrical method.

After the formal and material elements of life have been separately discussed, there comes an account of the process by which they are first brought into connexion, for this is how Aristotle views generation. With him it is the information of matter by psychic force; and his notions about the part which each parent plays in the production of a new being are vitiated throughout by this mistaken assumption. Nevertheless his treatise on the subject is, for its time, one of the most wonderful works ever written, and, as we are told on good authority,257 is now less antiquated than the corresponding researches of Harvey. The philosopher’s peculiar genius for observation, analysis, and comparison will partly account for his success; but, if we mistake not, there is another and less obvious reason. Here the fatal separation of form and matter was, except at first starting, precluded by the very idea of generation; and the teleological principle of spontaneous efforts to realise a predetermined end was, as it happened, perfectly in accordance with the facts themselves.

And now, looking back on his cosmology, we can see that Aristotle was never so near the truth as when he tried to bridge over the gulf between his two spheres, the one corruptible and the other eternal, by the idea of motion considered as a specific property of all matter, and persisting through all364 time; as a link between the celestial revolutions and the changes occurring on or near the earth’s surface; and, finally, as the direct cause of heat, the great agent acting in opposition to gravity—which last view may have suggested Bacon’s capital discovery, that heat is itself a mode of motion.

Another method by which Aristotle strove to overcome the antithesis between life as a mechanical arrangement and life as a metaphysical conception, was the newly created study of comparative anatomy. The variations in structure and function which accompany variations in the environment, though statically and not dynamically conceived, bring us very near to the truth that biological phenomena are subject to the same general laws of causation as all other phenomena; and it is this truth which, in the science of life, corresponds to the identification of terrestrial with celestial physics in the science of general mechanics. Vitality is not an individualised principle stationed in the heart and serving only to balance opposite forces against one another; but it is diffused through all the tissues, and bestows on them that extraordinary plasticity which responds to the actions of the environment by spontaneous variations capable of being summed up in any direction, and so creating entirely new organic forms without the intervention of any supernatural agency.
V.

We have now to consider how Aristotle treats psychology, not in connexion with biology, but as a distinct science—a separation not quite consistent with his own definition of soul, but forced on him by the traditions of Greek philosophy and by the nature of things. Here the fundamental antithesis assumes a three-fold form. First the theoretical activity of mind is distinguished from its practical activity; the one being exercised on things which cannot, the other on things which365 can, be changed. Again, a similar distinction prevails within the special province of each. Where truth is the object, knowledge stands opposed to sense; where good is sought, reason rises superior to passion. The one antithesis had been introduced into philosophy by the early physicists, the other by Socrates. They were confounded in the psychology of Plato, and Aristotle had the merit of separating them once more. Yet even he preserves a certain artificial parallelism between them by using the common name Nous, or reason, to denote the controlling member in each. To make his anthropology still more complex, there is a third antithesis to be taken into account, that between the individual and the community, which also sometimes slides into a partial coincidence with the other two.

Aristotle’s treatise on the soul is mainly devoted to a description of the theoretical faculties—sense, and thought or reason. By sense we become acquainted with the material qualities of things; by thought with their forms or ideas. It has been already mentioned that, according to our philosopher, the organism is a system of contrary forces held in equilibrium by the soul, whose seat he supposes to be in the heart. We now learn that every sensation is a disturbance of this equilibrium. In other words, the sensorium being virtually any and every mode of matter, is raised from possibility to actuality by the presence of some one force, such as heat or cold, in sufficient strength to incline the balance that way. Here we have, quite in Aristotle’s usual style, a description instead of an explanation. The atomic notion of thin films thrown off from the object of sense, and falling on the organs of sight or touch, was but a crude guess; still it has more affinity with the discoveries of a Young or a Helmholtz than scholastic phrases about potentiality and actuality. That sensation implies a disturbance of equilibrium is, indeed, an important truth; only, the equilibrium must be conceived as a balance, not of possible sensations, but of molecular states; that is to say, it must be interpreted according to the atomic theory.

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Aristotle is more successful when he proceeds to discuss the imagination. He explains it to be a continuance of the movement originally communicated by the felt object to the organ of sense, kept up in the absence of the object itself;—as near an approach to the truth as could be made in his time. And he is also right in saying that the operations of reason are only made possible by the help of what he calls phantasms—that is, faint reproductions of sensations. In addition to this, he points out the connexion between memory and imagination, and enumerates the laws of association briefly, but with great accuracy. He is, however, altogether unaware of their scope. So far from using them to explain all the mental processes, he does not even see that they account for involuntary reminiscence, and limits them to the voluntary operation by which we recall a missing name or other image to consciousness.

So far, Aristotle regards the soul as a function, or energy, or perfection of the body, from which it can no more be separated than vision from the eye. It is otherwise with the part of mind whi............