April 22, 1922] 



NA TURE 



515 



Letters to the Editor. 



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Mind. 



There seems to me now to be some prospect of agree- 

 ment that, since all characters are equally products 

 nature (potentiality, capacity, predisposition, 

 ithesis) and fitting nurture, all must be equally 

 late, acquired, germinal, somatic, and inheritable, 

 that be the case, the problem of inheritance is 

 tied. Doubtless some biologists will continue 

 discuss such things as the transmission of char- 

 ters and the intensity of inheritance, but the 

 ipossibility of defining their terms and explaining 

 Ihat they mean will always vitiate their labours. 

 Whatever other tasks biology has before it, two 

 of prime importance : (a) to determine what 

 laracters are evoked in individuals by such influ- 

 ices as food, moisture, light, temperature, hormones, 

 injury, and the like, and (6) to trace the evolution 

 races, which implies tracing the changes in their 

 itures {i.e. in germ-plasms as indicated by changes 

 characters), which, since the nature of every race 

 the sum of its potentialities, in turn implies tracing 

 langes in potentialities for development. In both 

 lese tasks biology must seek its data from the sub- 

 sidiary sciences of physiology and psychology. 



The kinds of nurture with which we are most 

 familiar, and which we can most easily observe in 

 action, are injury and use. Here, therefore, we are 

 best able to note to what extent individuals are 

 capable of developing in response to given influences, 

 and to what extent species have altered with respect 

 to their capacities for development. Both injury 

 and use confer adaptability on the individual. Injury 

 need not detain us long. Many plants and some lower 

 animals are capable of developing greatly in response 

 to it. Thus a begonia or a sponge may be completely 

 regenerated from a fragment. A lobster can regener- 

 ate its claw and a lizard its tail. Higher animals 

 merely heal injuries by means of scars. In them 

 this capacity has undergone retrogression and has 

 been replaced (or supplemented) by that which 

 confers much more adaptability — the capacity of 

 developing in response to use. 



It would seem that the power of developing in 

 response to use is a late and a high product of evolu- 

 tion. At any rate, since it is inappreciable in low, 

 and progressively more evolved in higher, animals, 

 presumably it must have had a beginning somewhere 

 in the scale. Presumably also, since a structure 

 cannot be used before it exists, the individual re- 

 capitulates in this particular, as in others, the 

 evolution of his race. 



The evidence is much clearer as regards mind. 

 I take it that mind is associated with movement ; 

 its function is to cause the individual to take action. 

 A reflex action may be associated with consciousness. 

 Some reflex actions {e.g. sneezing) are even initiated 

 by consciousness. Some {e.g. breathing) can be con- 

 trolled to some extent by the will ; but no reflex 

 action is initiated by the will. Thus, when we cough 

 at will the action is not reflex. Reflex actions, there- 

 fore, may be defined as those which are initiated by 

 stimuli other than will. On the other hand, an 

 instinct is always and altogether a mental thing — a 

 mental impulse, an emotion, an inclination, a desire 

 to do a certain action, the instinctive action. Like 



NO. 2738, VOL. 109] 



reflexes, it develops in the individual apart from 

 mental experience which merely awakens it to activity, 

 but does not create it. In other words, an instinct is 

 not learned ; it is not a product of the functional 

 activity of the mind, but develops in response to 

 quite different influences {e.g. hormones). It is not a 

 complex reflex ; some reflex actions {e.g. sneezing) 

 are quite as complex as some instinctive actions {e.g. 

 infantile crying). An instinctive action differs from 

 a reflex action in that it is always voluntary. The 

 individual performs the action because he wants to 

 do so. If there were no desire, there would be no 

 action. I am aware that all this is unorthodox. 

 Nevertheless, it is true, as any one may discover by 

 examining his own instincts. Does he not, for 

 example, eat, and drink, and sport, and make love 

 through desire ? Did he learn to feel these desires ? 

 I am aware also that at this stage it is customary 

 to discuss the metaphysics of mind and will. I have 

 tried to do so elsewhere, but it is unnecessary here. 

 It is enough that mind, including will, exists and 

 appears to influence the body as gravitation appears 

 (as incomprehensibly) to influence the planets. In- 

 stinct may be defined as desire which develops in 

 response to influences other than functional activity. 



Habit, intelligence, and reason are in a different 

 category. They are all products of learning, of 

 mental growth due to the functional activity of the 

 mind. An animal is intelligent in proportion as it 

 profits mentally from experience — that is, in pro- 

 portion as its past sheds a light on, and serves as a 

 -guide for, its present and its future. The animal 

 then stores experiences and recollects them. Thus 

 its mind grows. We have given a special name to 

 the power of growing mentally in response to use, 

 though the word is used somewhat vaguely. We 

 call it memory. We speak of a man with a good 

 or bad memory, with good or poor powers of learning. 



There are two sorts of memory, conscious and sub- 

 conscious. Again I am unorthodox, but my words 

 have real meanings. We learn two sorts of things : 

 (a) facts and the like, which we can recall to mind 

 and which belong to the conscious memory, and {b) 

 skill and facility in thinking and doing (mental habits) 

 which cannot in the same sense be recalled, and 

 which, therefore, belong to the subconscious memory. 

 For example, I can recollect a good deal about golf 

 clubs, balls, courses, and adventures ; but all this 

 is quite distinct from other sorts of learning, which I 

 cannot in the same sense recall, and, therefore, can- 

 not describe, which enable me to play skilfully (to 

 a humiliatingly small degree). The greatest golfers 

 do not know the very names of the muscles which 

 they have learned to co-ordinate with such exactness 

 and facility. 



Consider the caterpillar. He comes out of the egg 

 and, equipped with instincts, at once sets about the 

 business of life. He seeks his food and devours it ; 

 he hides from enemies ; at the proper time and place 

 he builds a cocoon, and as a butterfly does all sorts 

 of new actions of which also he can have had no 

 previous experience. Apparently he learns nothing ; 

 he has little or no memory. Learning would be use- 

 less to him ; for, unprotected and untaught as he is, 

 he must always act correctly and at once, or perish. 

 He can " bear in mind " for a little while, as a sound 

 lingers on a harp-string. But he cannot recall, as a 

 sound is reproduced by a gramophone. He can feel 

 {e.g. pleasure and pain, desire and aversion), but he 

 cannot think (compare, associate, imagine, and the 

 like) ; for without learning he has nothing to think 

 about. Because his past is a blank he cannot fore- 

 cast his future, which, therefore, is a blank also. He 

 lives only in the immediate present — a knife-edge of 

 time. Since he has little or no power of profiting by 



