that the "external world" to which plants and animals respond is also to be resolved into changes in their physical basis, I am quite willing to admit this possibility; as I am ready to admit that, for anything I know to the contrary, the reality of both the external world and the physical basis itself may consist in being perceived or known, but I hold it unwise to forget that the same daily experience which justifies our confidence in the orderly sequence of external nature also warrants the assumption that their external world is the same as ours. The question whether its. reality is ideal or material or both has no more to do with this purely practical confidence than has the presence or absence in a dog or an oak tree of conscious belief in it. They who hold the faith that science will some day be able to demonstrate, in the structure of the brain, the origin of such actions as writing a review of Huxley's Essays, are quite welcome to their faith; but I hold, as a purely practical matter, that they may find out in a much shorter way why I have written this article; and I also hold that this is likely to be the case for some considerable time. I also believe with Aristotle that the most practical way within our reach of studying that adjustment between the organism and the external world that fitness-which constitutes life, is to learn all we can about the physical basis and all we can about its fitness; and I hold fast to this purely practical confidence without any faith in the unknown biology of the distant future, and most assuredly without any desire to discount it. I must ask, however, what reason there is for thinking that belief that my volition is both real and part of the cosmic process is logically absurd. The greatest of all my many great debts to Huxley is the clear perception that there is no antagonism between belief that all the phenomena of nature, including those of life and mind, are mechanical, and my confidence in the value of my reason. If Huxley is right in the assertion that mechanical principles are nothing more than generalized statements of our experience, — as I am convinced that he is, and if the widest of all generalizations from my experience is that my volition counts; how can belief in the value of my reason be logically absurd? May not the logical absurdity lie with them who hold that proof that my rational actions are no more than might have been expected from the working of the mechanism of my body, would also prove that my reason is "as completely without any power to modify that working, as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery"? LECTURE III NATURE AND NURTURE THIS chapter, which all who have attended my lectures during the last ten years will find familiar, does not deal with the interminable question whether "acquired characters" are inherited, but, granting that this may be the case, it is an attempt to weigh the value of this "factor" in natural history. Herbert Spencer tells us that the segmentation of the backbone is the inherited effect of fractures, caused by bending, but Aristotle has shown ("Parts of Animals," I. i.) that Empedocles and the ancient writers err in teaching that the bendings to which the backbone has been subjected are the cause of its joints, since the thing to be accounted for is not the presence of joints, but the fitness of the joints for the needs of their possessor. It is an odd freak of history that we of the end of the nineteenth century are called upon to reconsider a dogma which was not only repudiated two thousand years ago, but was even then called antiquated. "Is there anything whereof it may be said: See! this is new? It hath been already of the old time which was before us." In this day of laboratories, are we not in danger of forgetting the first principle, so clearly put by Aristotle, that the thing to be explained is not the structure of organisms, but the fitness of this structure for the needs of living things in the world in which they pass their lives? We must be on our guard lest the great discovery that protoplasm is the physical basis of life obscure the truth that what Huxley has called the physical basis is one thing, while what Aristotle has called the essence of life is quite another thing. The physical basis of a locomotive engine is the expansion of steam, but its essence is fitness for the service of man. |