Professor Schmidt is, however, so far from clearly and consistently recognizing the exact limit of the theory, that within the compass of a single page he first affirms the limitation, and then denies it. First vindicating Darwin from the attack of Max Müller as to beginning and end of living organism, he says, "The origin of life has in fact nothing to do with actual Darwinism, or natural selection, unless the principle of selection be extended to the inorganic world of matter,"[BH] an entanglement which Schmidt is willing to avoid, and which Darwin carefully shuns, distinctly stating that "Science in her present state does not countenance the belief that living creatures are now ever produced from inorganic matter."[BI] But Schmidt has no sooner placed himself behind this line of defence, than he attacks Darwin for acknowledging origin of life by creation, maintaining that "it is directly incompatible with the doctrine of descent."[BJ] The theorist must take either one side or the other. Either he must maintain that the theory of descent has "nothing to do with the origin of life," and in that case there is no conflict with religious thought; or that the theory of descent is incompatible with creation, and in that case there is conflict with religious thought, and at the same time inconsistency with science, in respect of its own definition as an explanation of nature, and in respect of its own results which do not involve "spontaneous generation," but do include the position that not a single particle of matter can be originated or destroyed by any power recognized in operation. No one will "dispute the claims of the investigation of nature to its logical inferences," but "where the material substratum is deficient," most reasonable men will demand that distinct acknowledgment be made of the fact, and that the boundaries of science be defined accordingly. If, however, any one be inclined to maintain that "where the material substratum is deficient," all inquiry must terminate, and human thought must refuse to go further, or to attempt to rise higher, this certainly is not science, but an illogical attempt to make the science of nature commensurate with the boundaries of thought,--an arbitrary declaration that "the causal series" within the material universe is the sum total of causality. Such an affirmation can not warrantably attach itself to a theory of descent, as it can not be tested by observational methods, but altogether by reference to the laws of thought determining the value of rationalizing processes. The theory of "natural evolution," implies evolution from something; it postulates a beginning from which it takes procedure, and it exhausts itself in observations concerning such deviations as occur in the annals of natural history. If, therefore, any of "the partisans of natural evolution," take up a position involving denial of a rational acknowledgment of the supernatural, they isolate themselves in so doing,