August 7, 1896.] 



SCIENCE. 



151 



sensations derived from external objects 

 into movements of the body. 



The sensory nerves furnish the animal or 

 man all knowledge of the external world. 

 The brain, sitting in absolute darkness, 

 judges these sensations, and sends out cor- 

 responding impulses to action. The sensory 

 nerves are the brain's sole teachers ; the 

 motor nerves and through them the muscles 

 are the brain's only servants. The un- 

 trained brain learns its lessons poorly and 

 its commands are vacillating and ineffective. 

 In like manner the brain which has been 

 misused shows its defects in ill- chosen 

 action, the action against which nature pro- 

 tests through her whip of misery. In this 

 fact that nerve alteration means ineffective 

 action, lying brain and lying nerves, rests 

 the great argument for temperance, the 

 great argument against all forms of nerve 

 tampering, from the coffee habit to the 

 ' protracted meeting.' 



The senses are intensely practical in their 

 relation to life. The processes of natural 

 selection make and keep them so. Only 

 those phases of reality which our ancestors 

 could render into action are shown to us by 

 our senses. If we can do nothing in any 

 case, we know nothing about it. The 

 senses tell us essential truth about rocks 

 and trees, food and shelter, friends and 

 enemies. They answer no problems in 

 chemistry. They tell us nothing about 

 atom or molecule. They give us no ulti- 

 mate facts. Whatever is so small that we 

 cannot handle it is too small to be seen. 

 Whatever is too distant to be reached is 

 not truthfully reported. The ' X-rays ' of 

 light we cannot see, because our ancestors 

 could not use them. The sun and stars, the 

 clouds and the sky, are not at all what they 

 appear to be. The truthfulness of the 

 senses fails as the square of the distance in- 

 creases. Were it not so we should be 

 smothered by truth. We should be over- 

 whelmed by the multiplicity of our own 



sensations, and truthful response in action 

 would become impossible. Hyperesthesia 

 of any or all of the senses is a source of con- 

 fusion, not of strength. It is essentially a 

 phase of disease and shows itself in ineffec- 

 tiveness, not in increased power. Besides 

 the actual sensations, the so-called realities, 

 the brain retains also the sensations which 

 have been and are not wholly lost. Memory 

 pictures crowd the mind, mingling with 

 pictures which are brought in afresh by the 

 senses. The force of suggestion causes the 

 mental states or conditions of one person to 

 repeat themselves in another. Abnormal 

 conditions of the brain itself furnish another 

 series of feelings with which the brain must 

 deal. Moreover the brain is charged with 

 impulses to action, passed on from genera- 

 tion to generation, surviving because they 

 are useful. With all these arises the 

 necessity for choice as a function of the 

 mind. The mind must neglect or suppress 

 all sensations which it cannot weave into 

 action. The dog sees nothing that does 

 not belong to its little world. The man in 

 search of mushrooms, ' tramples down oak 

 trees in bis walks.' To select the sensations 

 that concern us is the basis of the power of 

 attention. The suppression of undesired 

 actions is the function of the will. To find 

 data for choice among the possible motor 

 responses is a function of the intellect. In- 

 tellectual persistency is the essence of in- 

 dividual character. 



As the conditions of life become more 

 complex it becomes necessary for action 

 to be more carefully selected. Wisdom 

 is the parent of virtue. Knowing what 

 should be done logically precedes doing it. 

 Good impulses and good intentions do not 

 make action right or safe. In the long run 

 action is tested, not by its motives, but by 

 its results. 



The child when he comes into the world 

 has everything to learn. His nervous sys- 

 tem is charged with tendencies to reaction 



