426 AMERICAN ANTHROPOLOGIST [n. s., i, 1899
of his original stock, and indeed with some gain to himself; it was long ago observed, too, that in time the scholastic teacher becomes stale, loses mental elasticity, and must be superannuated or discarded ; while much recent experience indicates that the teacher of nature finds his theme an inexhaustible well-spring of knowledge and continues to acquire and impart the facts of nature with little loss of efficiency, and indeed with certain gain, until senility settles on the faculties of body and brain at once. These and many other experiences verify the marvelous prevision of Bacon, and go far toward proving that the mind, with its wealth of inherited and acquired knowledge, is but the product of inter- action between its own hierarchy of organs and the great external ; at the same time they remove an apparent obstacle in the way of considering mental power as indefinitely extensible with the pro- gressive growth of its own proper organ and the ancillary organs of the human body. Accordingly it would seem timely and profitable to recognize a law of mind, comparable with certain other fundamental laws which have been incorporated into the body of science ; one of these is the law of indestructibility of matter ; another is the law of conservation of energy, or " persist- ence of motion " if the latest formula be adopted ; that which is now enounced is the law of cumulation of mind. The summation of experience expressed in this formula of mentality is compre- hensive ; under postulates which seem axiomatic, it is in accord with the prehistoric development of protohuman and human crania, with the beautification of the human body, with the recon- struction of the primitive somatikos by demotic interaction, and with cephalization and cheirization in their multifarious aspects, as well as with the purely intellectual development of mankind. The reduction of the formula to quantitative terms is a task for the future.
The current of human experience with respect to the progress of the human mind is strong and unmistakable ; mental power is increasing with the multiplication of interactions, and, like the
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