Attempting to define this trait, we may say that it is the perception of the unity and continuity of the individual’s psychological activities. Just in proportion as this perception becomes clear, positive, sharply defined, does the individual become aware of his own life, his real existence, its laws, and its purposes. Hence the study of this mental characteristic becomes of the highest importance in ethnology; for it has been well said (Post) that the growth or decay of individual self-consciousness is an unfailing measure of the growth or decay of States. Physiologically, the sense of self, the Ego, is produced by outgoing discharges from the central nervous system which are felt. They may arise from external forces or from the internal source which we call Volition, or Will. In both cases the repetition of _feeling_ them yields the notion of Personality. It is instructive to note how differently races and nations have understood and still do understand this notion; instructive, because it has much to do with their characters and actions. Naturally enough many have identified the _I_ with the body, or with that portion of the body least destructible, the bones. For this reason, in Egypt, Peru, Teneriffe, and many other localities there was the practice of preserving the entire body by exsiccation or mummification, the belief being that, were it destroyed, the personal existence of the decedent would also perish. In other lands the bones were carefully guarded in ossuaries or shrines, for in them the soul was held to abide. Not less widely received was another opinion, that the self dwells in the name. The personal name was therefore conferred with ceremony, and frequently was not disclosed beyond the family. The individual could be injured through his name, his personality impaired by its misuse. In higher conditions the Person is usually defined by attributes and environment, as sex, age, calling, property, and the like. Ask a man who he is, he will define himself “by name and standing.” Few reach the conception of abstract Individuality, apart from the above incidents of time and place; so that it is easy to see that self-consciousness is still in little more than an embryonic stage of development in humanity. It differs notably in races and stages of culture. Dr. Van Brero comments on the slight sense of personality among the Malayan islanders, and attributes to that their exemption from certain nervous diseases. Its morbid development in self-attention and Ego-mania is frequently noticed in the asylums of highly civilised centres.