24 Heredity. 



blems, even writes pages of philosophy, like Condillac. All this is 

 done as well as and even better than in the waking state, and with 

 as remarkable steadiness as in the case of instinct The somnam- 

 bulist, moreover, during the crisis, performs only acts which are 

 habitual with him : the poet does not compose music, the musician 

 does not write verses, nor did Condillac ever awake and find 

 himself embroidering. Finally, it also resembles instinct, in that 

 all its acts are performed unconsciously. If somnambulism were 

 permanent and innate, it would be impossible to distinguish it 

 from instinct The resemblance was pointed out by Cuvier. 

 'We can gain a clear notion of instinct,' he well observes, 'only by 

 admitting that animals have in their sensorium images, or constant 

 sensations, which determine their action, as ordinary and accidental 

 sensations determine action in general. It is a sort of dream or 

 vision, which haunts them constantly, and, so far as concerns their 

 instinct, animals may be regarded as a kind of somnambulists.' 

 ' The organization of animals,' says Miiller, ' is singularly favour- 

 able to the realization of the images, ideas, and inclinations which 

 appear in the sensorium. As the internal and the external depend 

 upon one and the same final cause, the form of the animal perfectly 

 corresponds with its propensities. Thus, the instinctive pro- 

 pensities of the spider represent to it, like a sort of dream, the 

 theme of its actions the construction of its web.' 



Here, again, in the case of somnambulism, all that is needed 

 in order to bring about the metamorphosis of intellectual into 

 instinctive acts is, that intelligence should be reduced to a few 

 special acts (making verses, composing music, or the like), and 

 that it should become unconscious. The phenomena of habit, 

 which have been so justly compared with those of instinct, exhibit 

 equally the transformation of intelligence into instinct So soon 

 as any intellectual operation, by repetition (that is to say, by 

 restricting its domain), has become automatic (that is to say, 

 unconscious), then the act is habitual or instinctive. 



Hence it is less difficult than is generally supposed to conceive 

 how intelligence may become instinct : we might even say that, 

 leaving out of consideration the character of innateness, to which 

 we will return, we have seen the metamorphosis take place. 

 There can, then, be no ground for making instinct a faculty apart, 



