To most people Darwinism and evolution mean one and the same thing. After what has here been said, however, with regard to the pre-Darwinian evolutionary movement, and the distinction between the doctrines of descent with modification and of natural selection, it need hardly be added that the two are quite separate and separable in thought, even within the limits of the purely restricted biological order. Darwinism is only a part of organic evolution; the theory, as a whole, owes much to Darwin, but it does not owe everything to him alone. There were biological evolutionists before ever he published the \'Origin of Species;\' there are biological evolutionists even now who refuse to accept the truth of his great discovery, and who cling firmly to the primitive faith set forth in earlier and cruder shapes by Erasmus Darwin, by Lamarck, or by Robert Chambers.

Much more, then, must Darwinism and the entire theory of organic development to which it belongs be carefully discriminated, as a part or factor, from evolution at large, as a universal and all-embracing cosmical system. That system itself has gradually emerged as a[Pg 178] slow growth of the past two centuries, a progressive development of the collective scientific and philosophical mind of humanity, not due in its totality to any one single commanding thinker, but summing itself up at last in our own time more fully in the person and teaching of Mr. Herbert Spencer than of any other solitary mouthpiece. Indeed, intimately as we all now associate the name of Darwin with the word \'evolution,\' that term itself (whose vogue is almost entirely due to Mr. Spencer\'s influence) was one but rarely found upon Darwin\'s own lips, and but rarely written by his own pen. He speaks rather of development and of natural selection than of evolution: his own concern was more with its special aspect as biological modification than with its general aspect as cosmical unfolding. Let us ask, then, from this wider standpoint of a great and far-reaching mental revolution, what was Charles Darwin\'s exact niche in the evolutionary movement of the two last centuries?

Evolutionism, as now commonly understood, may be fairly regarded as a mode of envisaging to ourselves the history of the universe, a tendency or frame of mind, a temperament, one might almost say, or habit of thought rather than a definite creed or body of dogmas. The evolutionist looks out upon the cosmos as a continuous process unfolding itself in regular order in obedience to definite natural laws. He sees in it all, not a warring chaos restrained by the constant interference from without of a wise and beneficent external power, but a vast aggregate of original elements, perpetually working out their own fresh redistribution, in accordance with their own inherent energies. He regards[Pg 179] the cosmos as an almost infinite collection of material atoms, animated by an almost infinite sum-total of energy, potential or kinetic.

In the very beginning, so far as the mental vision of the astronomer can dimly pierce with hypothetical glance the abyss of ages, the matter which now composes the material universe seems to have existed in a highly diffuse and nebulous condition. The gravitative force, however, with which every atom of the whole vast mass was primarily endowed, caused it gradually to aggregate around certain fixed and definite centres, which became in time the rallying-points or nuclei of future suns. The primitive potential energy of separation in the atoms of the mass was changed into actual energy of motion as they drew closer and closer together about the common centre, and into molecular energy or heat as they clashed with one another in bodily impact around the hardening core. Thus arose stars and suns, composed of fiery atomic clouds in a constant state of progressive concentration, ever gathering-in the hem of their outer robes on the surface of the solid globe within, and ever radiating off their store of associated energy to the impalpable and hypothetical surrounding ether. This, in necessarily brief and shadowy abstract, is the nebular theory of Kant and Laplace, as amended and supplemented by the modern doctrine of the correlation and conservation of energies.

Applied to the solar system, of which our own planet forms a component member, the evolutionary doctrine (in its elder shape) teaches us to envisage that minor group as the final result of a single great diffuse[Pg 180] nebula, which once spread its faint and cloud-like mass with inconceivable tenuity, at least as far from its centre, now occupied by the sun\'s body, as the furthest point in the orbit of Neptune, the outermost of the yet known planets. From this remote and immense periphery it has gradually gathered itself in, growing denser and denser all the time, towards its common core, and has left behind, at irregular intervals, concentric rings or belts of nebulous matter, which, after rupturing at their weakest point, have hardened and concentrated round their own centre of gravity into Jupiter, Saturn, the Earth, or Venus. The main central body of all, retreating ever within as it dropped in its course the raw material of the planetary masses, has formed, at last, the sun, the great ruler and luminary of our system. Much as this primitive evolutionary concept of the development and history of the solar system has been modified and altered of late years by recent researches into the nature of comets and meteors and of the sun\'s surface, it still remains for all practical purposes of popular exposition the best and simplest mental picture of the general type of astronomical evolution. For the essential point which it impresses upon the mind is the idea of the planets in their several orbits and with their attendant satellites as due, not to external design and special creation, in the exact order in which we now see them, but to the slow and regular working out of preordained physical laws, in accordance with which they have each naturally assumed, by pure force of circumstances, their existing size, and weight, and orbit, and position.

Geology has applied a similar conception to the[Pg 181] origin and becoming of the earth\'s material and external features as we now know them. Accepting from astronomy the notion of our planet\'s primary condition as a cooling sphere of incandescent matter, it goes on to show how the two great envelopes, atmospheric and oceanic, gaseous and liquid, have gradually formed around its solid core; how the hard crust of the central mass has been wrinkled and corrugated into mountain chain and deep-cut valley, uplifted here into elevated table-land or there depressed into hollow ocean bed; how sediment has slowly gathered on the floor of the sea, and how volcanic energies or lateral pressure have subsequently forced up the resulting deposits into Alpine peaks and massive continents. In this direction, it was Lyell who principally introduced into science the uniformitarian or evolutionary principle, who substituted for the frequent cataclysms and fresh beginnings of the earlier geologists the grand conception of continuous action, producing from comparatively infinitesimal but cumulative causes effects which at last attain by accretion the most colossal proportions.

Here biology next steps in, with its splendid explanation of organic life, as due essentially to the secondary action of radiated solar energy on the outer crust of such a cooling and evolving planet. Falling on the cells of the simplest green plants, the potent sunlight dissociates the carbon from the oxygen in the carbonic acid floating in the atmosphere, and builds it up with the hydrogen of water in the tissues of the organism into starches and other organic products, which differ from the inert substances around them, mainly by the possession of locked-up solar energy. On[Pg 182] the energy-yielding food-stuffs thus stored up the animal in turn feeds and battens, reducing what was before potential into actual motion, just as the steam-engine reduces the latent solar energy of coal into visible heat and visible movement in its furnace and its machinery. How the first organism came to exist biology has not yet been able fully to explain for us; but aided by chemical science it has been able to show us in part how some of the simpler organic bodies may have been originally built up, and it does not despair of showing us in the end how the earliest organism may actually have been produced from the prime elements of oxygen, hydrogen, nitrogen, and carbon. Into this most fundamental of biological problems, however, Darwin himself, with his constitutional caution and dread of speculative theorising, was not careful or curious to enter. Even upon the far less abstruse and hypothetical question, whether all life took its prime origin from a single starting-point or from several distinct and separate tribal ancestors, he hardly cared so much as to hazard a passing speculation. With splendid self-restraint he confined his attention almost entirely to the more manageable and practical problem of the origin of species by natural selection, which lay then and there open for solution before him. Taking for granted the existence of the original organism or group of organisms, the fact of reproduction, and the tendency of such reproduction to beget increase in a geometrical ratio, he deduced from these elementary given factors the necessary corollary of survival of the fittest, with all its marvellous and far-reaching implications of adaptation to the environment and specific distinctions. By doing[Pg 183] so, he rendered conceivable the mechanism of evolution in the organic world, thus bringing another great aspect of external nature within the range of the developmental as opposed to the miraculous philosophy of the cosmos.

Psychology, once more, in the hands of Herbert Spencer and his followers, not wholly unaided by Darwin himself, has extended the self-same evolutionary treatment to the involved and elusive phenomena of mind, and has shown how from the simplest unorganised elements of feeling, the various mental powers and faculties as we now know them, both on the intellectual and on the emotional side, have been slowly built up in the long and ever-varying interaction between the sentient organism and the natural environment. It has traced the first faint inception of a nervous system as a mere customary channel of communication between part and part; the gradual growth of fibre and ganglion; the vague beginnings of external sense-organ and internal brain; the final perfection of eye and ear, of sight and hearing, of pleasure and pain, of intellect and volition. It has thus done for the subjective or mental half of our complex nature what biology, as conceived by Darwin, has done for the physical or purely organic half; it has traced the origin and development of mind, without a single break, from its first faint and half-unconscious manifestation in the polyp or the jelly-fish to its final grand and varied outcome in the soul of the poet or the intellect of the philosopher.

Finally, sociology has applied the evolutionary method to the origin and rise of human societies, with their languages, customs, arts, and institutions, their[Pg 184] governmental organisation and their ecclesiastical polity. Taking from biology the evolving savage, viewed as a developed and highly gifted product of the anthropoid stock, it has shown by what stages and through what causes he has slowly aggregated into tribes and nations; has built up his communal, polygamic, or monogamic family; has learnt the use of fire, of implements, of pottery, of metals; has developed the whole resources of oral speech and significant gesture; has invented writing, pictorial or alphabetic; has grown up to science, to philosophy, to morals, and to religion. The chief honours of this particular line of enquiry, the latest and youngest of all to receive the impact of the evolutionary impulse, belong mainly to Tylor, Lubbock, and Spencer in England, and to Haeckel, De Mortillet, and Wagner on the continent.

In the sublime conception of the external universe and its present workings which we thus owe to the independent efforts of so many great progressive thinkers, and which has here been briefly............