Apparently, then, voice, facial expression, gesture, and the like, which later become the vehicle of personal impressions and the sensible basis of sympathy, are attractive at first chiefly for their sensuous variety and vividness, very much as other bright, moving, sounding things are attractive; and the interpretation of them comes gradually by the interworking of instinct and observation. This interpretation is nothing other than the growth, in connection with these sensuous experiences, of a system of ideas that we associate with them. The interpretation of an angry look, for instance, consists in the expectation of angry words and acts, in feelings of resentment or fear, and so on; in short, it is our whole mental reaction to this sign. It may consist in part of sympathetic states of mind, that is in states of mind that we suppose the other to experience also; but it is not confined to such. These ideas that enrich the meaning of the symbol—the resentment or fear, for instance—have all, no doubt, their roots in instinct; we are born with the crude raw material of such feelings. And it is precisely in the act of communication, in social contact of some sort, that this material grows, that it gets the impulses that give it further definition, refinement, organization. It is by intercourse with others that we expand our inner experience. In other words, and this is the point of the matter, the personal idea consists at first and in all later development, of a sensuous element or symbol with which is connected a more or less complex body of thought and sentiment; the whole social in genesis, formed by a series of communications. What do we think of when we think of a person? Is not the nucleus of the thought an image of the sort just mentioned, some ghost of characteristic expression? It may be a vague memory of lines around the mouth and eyes, or of other lines indicating pose, carriage, or gesture; or it may be an echo of some tone or inflection of the voice. I am unable, perhaps, to call up any distinct outline of the features of my best friend, of my own mother, or my child; but I can see a smile, a turn of the eyelid, a way of standing or sitting, indistinct and flitting glimpses, but potent to call up those past states of feeling of which personal memories are chiefly formed. The most real thing in physical presence is not height, nor breadth, nor the shape of the nose or forehead, nor that of any other comparatively immobile part of the body, but it is something in the plastic, expressive features: these are noticed and remembered because they tell us what we most care to know.