Yet what could be more enigmatic than the rock record as it stands? For in nature it possesses none of that idealized integrity and coherence, with which geology has invested it for the purpose of making it understandable. Rather it is a mighty chaos of scattered and fragmentary fossiliferous formations, whose baffling complexity, discontinuity, and ambiguity tax the ingenuity of the most sagacious interpreters. Transformism is the key to one possible synthesis, which might serve to unify that intricate mass of facts, but it is idle to pretend that this theory is the unique and necessary corollary of the facts as we find them. The palæontological argument is simply a theoretical construction which presupposes evolution instead of proving it. Its classic pedigrees of the horse, the camel, and the elephant are only credible when we have assumed the “fact” of evolution, and even then, solely upon condition that they claim to approximate, rather than assign, the actual ancestry of the animals in question. In palæontology, as in the field of zoölogy, evolution is not a conclusion, but an interpretation. In palæontology, otherwise than in the field of genetics, evolution is not amenable to the check of experimental tests, because here it deals not with that which is, but with that which _was_. Here the sole objective basis is the mutilated and partially obliterated record of a march of events, which no one has observed and which will never be repeated. These obscure and fragmentary vestiges of a vanished past, by reason of their very incompleteness, lend themselves quite readily to all sorts of theories and all sorts of speculations. Of the “Stone Book of the Universe” we may say with truth that which Oliver Wendell Holmes says of the privately-interpreted Bible, namely, that its readers take from it the same views which they had previously brought to it. “I am, however, thoroughly persuaded,” say the late Yves Delage, “that one is or is not a transformist, not so much for reasons deduced from natural history, as for motives based on personal philosophic opinions. If there existed some other scientific hypothesis besides that of descent to explain the origin of species, many transformists would abandon their present opinion as not being sufficiently demonstrated.... If one takes his stand upon the exclusive ground of the facts, it must be acknowledged that the formation of one species from another species has not been demonstrated at all.” (“L’herédité et les grands problèmes de la biologie générale,” Paris, 1903, pp. 204, 322.) II THE PROBLEM OF ORIGINS CHAPTER I THE ORIGIN OF LIFE § 1. The Theory of Spontaneous Generation