The manner in which this problem, from a materialistic point of view, can and must be treated, is not so complicated as we might imagine. The central thought in all materialistic discussions and investigations may be briefly expressed as follows: Life is a material force and nothing else. If this be true, then of course materialism is the only true religion. Whether God or some other higher being exists, must then become a question of little or no consequence. Man knows in any case his own origin and fate. The fundamental religious doctrines will then read: In matter alone dwell all the forces of nature and spirit; in matter alone can these forces appear and reveal themselves; nature knows of no[52] supernatural beginning or continuation; it produces everything; consumes everything; is itself beginning and end, cradle and grave; by its own power nature produces man, by its own power it receives him back again. Against these and similar statements there would be no objection, if it could be shown that life really has its source in the material world. But if it can be demonstrated that life never does, nor ever could by any possibility, originate in lifeless matter, then it is evident that we must look for some other source.
Let it be our object, then, fully to investigate this problem.
If living beings are produced by material forces, experience must verify the fact that matter really creates life of itself. In other words, the “to be or not to be” of materialism is identical with the old question of generatio aequivoca or spontanea, i. e., whether there exists in nature a spontaneous or parentless generation of living beings.
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Generatio aequivoca covers the entire ground of the materialists. Here the doctrine has not only its principal roots but all of them.
If the materialists lose this foothold, all their natural science resources are emptied at once, so important is generatio spontanea for materialism. Only under this form and with this substance can natural science have anything in common with materialism, which latter, strictly speaking, is only a religious doctrine, although as such purely negative. But just for this reason science has for centuries labored to decide whether this doctrine is false or true.
The question is, does or does not this spontaneous generation exist? Scientific research has, in all times, occupied itself with this question in different forms and modes.
The farther we go back in time the more general we find the opinion that life may arise spontaneously from inorganic matter. That such an idea[54] should prevail, is, of course, easy to understand. Very little was known about the propagation of the lower animals and plants. Especially the very peculiar and complicated development of the parasites and their passive migrations were practically unknown.
It seemed impossible to understand whence these beings had come, so the nearest explanation was resorted to, that is to say, that wherever they were found, they had come into existence “of themselves.” Neither was it so clearly understood then as now that eggs and seeds are living beings as well as the fully developed animals and plants. It was thought that grain must decay in the earth, yea, that this was the necessary condition for the growth of the plant.
Thus people had daily before their eyes cases where living beings were generated by substances that seemed inert and dead.
But with a better and more complete knowledge of organisms and especially[55] of the extremely complicated mode of propagation characteristic of insects, doubts as to generatio spontanea increasingly arose. It was, however, at a comparatively late time, or in the middle of the seventeenth century, that Harvey formulated his famous thesis, “omne virum ex oro,” or, as it has been later said, “omne vivum ex vivo,” which we may translate thus: “Life implies life; all living beings descend from previous existing parents,” or negatively, “No living being is generated from lifeless matter.” Thus, for the first time, the idea was pronounced by natural science that life is a specific force; an independent principle, that has not its roots in the material world.
As generatio aequivoca leads to materialism, so Harvey’s formula leads to pure idealism. That these consequences should have been seen from the beginning, was so much the less to be expected since even today no such discovery has been made or could have been made, simply because no attention[56] has been given to it. Hitherto the only question has been: Is Harvey’s formula a fact verified by natural science or not? In this form the battle has raged for over two centuries, often with great vehemence, and victory has leaned now to one side, now to the other. Finally, it was agreed that parentless generation was not to be found among the higher forms of animals and plants which could be observed with the naked eye. Büchner himself says it has not hitherto been discovered that any higher or more developed organism may be created by inorganic matter and forces alone.
“Today,” he says, “it seems to be a general law of the inorganic world that everything living originates from a parental embryo or else is directly segregated from the mother-body.”
But although spontaneous generation of the higher animals and plants seemed doubtful even to Büchner, nothing was at this time settled in regard to the origin of the lower organisms.[57] With the discovery of the microscopical organic world, a new field and one more difficult of access was opened for research. It was now the sudden and unexpected appearance of bacteria, aspergillus and infusoria in places where their previous existence could not be imagined, that maintained the belief in generatio spontanea. But by and by we learned to understand the propagation and life also of these low organisms, their ability to withstand very high or very low temperatures, and the facility with which they are spread by the air and, above all, their rapid propagation. It commenced to be more and more evident that even in the micro-organic world no parentless generation exists. The investigations by Spallanzani, and later by Schultze, Schwann, von Dusch and Schr?der, were epochal for the establishing of this fact. Their method, however, left some room for criticism which was forcefully pointed out by a[58] great number of scientists, especially by the Englishman Needham.
During all these disputes Harvey’s formula had, however, won such a stability and approbation that Büchner himself under its pressure formulated his position in the following cautious words: “Even if recent scientific researches have more and more limited the ground for spontaneous generation, it is nevertheless not improbable that it even now takes place among the lowest and least developed organisms.”
It may willingly be conceded that this assertion was in its time by no means without foundation. But scarcely could Büchner or anybody else at that moment imagine how soon the hour of decision would strike. Shortly after 1860 the many centuries old question was finally settled almost simultaneously by Hoffman and Pasteur. Through the latter’s masterly investigations it was fully demonstrated that parentless generation does not exist in the micro-organic world either.[59] Before Pasteur’s simple and clear evidence, opposition was silenced even so far that the question has almost entirely ceased to occupy our attention. Omne vivum ex vivo appears now to be an unchallenged truth. Life implies life.
But although science thus rejected generatio spontanea, the materialists nevertheless occupy a very strong position on the selfsame foundation as formerly, and continue the defense apparently not without some success.
In spite of Büchner’s real, or perhaps partly pretended, confidence, he seems to have had a presentiment of how weak the support of generatio spontanea was, and we find him therefore suddenly reasoning as if its cause were already lost. Thus he makes the entirely sound remark that even if at the present time all animals and plants must have parents, yet nothing whatever is thereby demonstrated in regard to the very first appearance of life in the universe. “If all organic beings[60] have parents, how, then, did the first parents come into existence?” he asks. “When all outer conditions were favorable, might they not have appeared spontaneously, accidentally or necessarily? Or must the first organisms have been created through the intervention of some higher power?” Büchner concedes that this question is extremely complicated, and at first glance may appear unsolvable without the assumption of some such higher being who of his own will created the first organisms as it pleased him and endowed them with the faculty of propagation. “Orthodox scientists point with satisfaction also to this state of affairs,” says Büchner, “and they remind us at the same time of the artful and complicated structure of the world, and warmed by their conviction they see therein the wise arrangements of a higher, personal creator, who built the world according to his personal intentions.”
We might, according to Büchner,[61] dismiss these orthodox thinkers with the assumption “that the first elements endowed with the idea of the race have been present in space from all eternity in formless chaos out of which the universe slowly consolidated, and accidentally developed after the formation and cooling of the planet wherever conditions were favorable.” But such fictitious reasonings or pretexts, Büchner assures us, are not necessary. Scientific facts, he says, indicate with great distinctness that the organic beings on our earth owe their generation and propagation to the co-operation of physical substances and forces alone.
After such an introduction we proceed with interest to learn about these scientific facts, but how great is our disappointment when we find that Büchner here takes up an entirely different subject, which, if it has any connection with the question at issue, goes to prove just the reverse of what he intended. The whole long series of facts to which he now points is, in a[62] few words, nothing but Darwin’s theory in a paleontological light. What Büchner shows by numerous examples from fossil deposits, is that higher forms of animals and plants have slowly developed from lower forms. But what has this fact to do with generatio spontanea? That higher forms have developed from lower forms only confirms the dictum that life implies life; in other words, supports Harvey’s law. But it is something else that Büchner should have demonstrated. He should instead have shown us that the first organisms owe their existence to physical forces alone. But on this subject he uses only vague expressions, void of any real significance, about the slow cooling off of the earth; about the length of the geological periods, and about favorable conditions; but not a line to explain what this word “favorable” stands for.
Although Büchner here inadvertently supports something different from what he intended, his remark nevertheless remains true that the present mode of[63] propagation proves nothing in regard to the generation of the first organisms.
Other scientists have gone further than Büchner and believed themselves justified in extending Harvey’s law to cover not only the present time, but all times. And the problem as to the first organisms has been answered in various ways. Sir William Thomson believes that such might have come to the earth with some meteoric stone, possibly a moss-clad fragment, from another planet in the universe that had met with a cosmic catastrophe, and, further, he has even tried to show that this hypothesis does not involve any physical impossibility.
Opinions seem to be divided, then, as to the validity of Harvey’s law. This again indicates a deficiency in the law itself, and it is true that such a deficiency really exists. Harvey’s formula is not a law; it is, as yet, only an empirical hypothesis.
It is true that life presupposes life in all the cases we have been able to[64] investigate. These cases are exceedingly numerous because on the disbelief in generatio spontanea rests a whole modern industry, the art of preserving, which in millions of cases daily verifies the hypothesis. But our experience, in spite of this, does not reach far. If we continue our observations, who can guarantee that we would not finally discover that Büchner, after all, was right, and one single case would suffice. The utmost we can attain by observation is a certain degree of probability, and if we undertook to prove Harvey’s hypothesis to be a law in this way, our experiments must be extended in infinitum.
In order to reach certainty only under present conditions, we must study the generation of every now living organism, animals, plants, bacteria and the like. If it were found then that all these beings have had parents it would still be impossible to draw absolutely sure conclusions in regard to previous generations. We should be[65] obliged to extend our researches through antiquity and primeval ages. If then no gap was to be found in the series and we perhaps finally traced life back to the “moss-clad fragment” from another world, we would again face the question, how the beings on that planet, once in time, had come into existence? Perhaps there the elements and forces of nature were such as to create life spontaneously. This question, of course, could not be decided except through continued observations, which would be obliged to extend to every point of an infinite universe and back to the dawn of time. First, then, we should know that Harvey’s hypothesis was a law, valid without limitations in the past—but also only in the past—and valid with one single exception, namely, the very first organism, of which we presently shall speak. In regard to the law’s validity in the future, we should no doubt possess a knowledge that approached certainty, but it could not be called absolutely[66] sure. Because, even granted that no living being hitherto was without parents, it is not logically impossible that sometime in the future, lifeless matter might undertake to create organisms. To obtain certainty we must continue our observations until the end of time.