If then, the neuropath is merely displaying instincts which are common to all mankind, what is the difference between him and the normal human being? The difference is psychologically slight, sociologically immense. While his normal brother reacts instinctively and emotionally to his physical and social environment in such a way and to such a degree as to promote his own welfare and that of others, the neuropath does not. Nobody calls the townsman a neuropath who before crossing the street waits on the pavement until the stream of traffic has thinned. If he did not wait we should rather call him a fool. But the instinct of fear is largely at the bottom of his so-called intelligent caution—especially if he has ever witnessed a distressing street accident. But what do we say of the man who waits and waits until finally he is too afraid to advance, eventually stealing down to another place so that he may cross in safety? He is very likely to be called a neuropath. Or what shall we say of the unfortunate man whose caution has gone so far that he cannot cross _any_ open space whatever, and is said to be suffering from agoraphobia? Or again, take the case of a man whose personality, family or country, is grossly and publicly insulted. If he strikes at the aggressor, do we call him neuropathic? But we seldom hesitate to apply this term to the man who is inordinately touchy, ever on the watch for the least suspicion of insult towards himself or anything even remotely connected with him. The emotion of fear underlies both the attitude of caution and of “funk,” that of anger, the righteous indignation of the stalwart and the querulous, peevish irritability of the neurasthenic. The difference between the behaviour of the normal man and the neuropath lies primarily in the circumstances that provoke emotion in them, and secondly in the violence and duration of the emotion itself. We should remember also that many varieties of animals display the kind of behaviour we have described, and regard as so unusual, if not utterly eccentric, in our friends. Professor William James reminds us of the chronic agoraphobia of our domestic cats; and the tamer of wild animals has good reasons to respect the incessant touchiness of some species of the genus _Felis_. Do we invoke theories of visceral ptosis, intoxication and the rest to explain the behaviour of the average cat or mule? Scarcely. We say that these animals are actuated by instinct. Our arrogance makes it difficult for us to suppose that our suffering human brothers are also acting instinctively. Yet this is undoubtedly the case.