areas of brain surface, and knits up many associations, so that one idea calls up many other ideas. This leads us to recognize the psychological conditions of increased energy, which are, first, the presence of more ideas, second, the more facile flow of ideas; the whole accompanied by a state of marked pleasurableness. Pleasure is a notable effect of increased energy. When work progresses rapidly and satisfactorily, it is accomplished with great zest and a feeling almost akin to exaltation. These conditions describe to some degree the conditions when we are doing efficient work. Since we are endowed with the energy requisite for such efficient work, the obvious question is, why do we not more frequently use it? The answer is to be found in the fact that we have formed the habit of giving up before we create conditions of high efficiency. You will note that the conditions require long-continued exertion and resolute persistence. This is difficult, and we indulgently succumb to the first symptoms of fatigue, before we have more than scratched the surface of our real potentialities. Because of the prominent place occupied by fatigue in thus being responsible for our diminished output, we shall briefly consider its place in study. Everyone who has studied will agree that fatigue is an almost invariable attendant of continuous mental exertion. We shall lay down the proposition at the start, however, that the awareness of fatigue is not the same as the objective fatigue in the organs of the body. Fatigue should be regarded as a twofold thing--a state of mind, designated its subjective aspect, and a condition of various parts of the body, designated its objective aspect. The former is observable by introspection, the latter by analysis of bodily secretions and by measurement of the diminution of work, entirely without reference to the way the mind regards the work. Fatigue subjectively, or fatigue as we _feel_ it, is not at all the same as fatigue as manifested in the body. If we were to make two curves, the one showing the advancement of the _feeling_ of fatigue, and the other showing the advancement of impotence on the part of the bodily processes, the two curves would not at all coincide. Stated another way, fatigue is a complex thing, a product of ideas, feelings and sensations, and sometimes the ideas overbalance the sensations and we think we are more tired then we are objectively. It is this fact that accounts for our too rapid giving up when we are engaged in hard work.