The heart beats regularly and at short intervals, but after each beat its muscles come into a state of complete relaxation and enjoy a refreshing rest, even though it be but for a moment. Likewise the lungs seem to be unceasing in their activity, but a careful study of their action discloses the fact that every contraction is followed by a perfect relaxation, and that the rest secured between successive respirations is adequate for recuperations. In all bodily processes the same alternation is discovered. No bodily activity is at all con- <p 211> tinuous. Mental processes, too, can be continued for but a very short time. By attempting to eliminate these periods of rest for bodily and mental acts, we merely exhaust without a corresponding increase in efficiency. The laws of nature are firm and countenance no infringement. The periods between activity and rest, as well as the durations of the two processes, may be changed. Thus, up to a certain limit, the periods devoted to activity may follow more rapidly and endure longer. There is, however, a danger point which may not be passed with impunity. The danger signal may manifest itself in several ways: The over- trained athlete becomes ``stale''; the over- worked brain worker becomes nervous; the overworked laborer becomes indifferent and generally inefficient. In all these and in similar instances, the amount of energy expended is out of proportion to the results of the labor. The athletic trainer has learned to guard against overtraining and is severely condemned for making <p 212> such a mistake. The brain worker often regards overwork as a commendable thing. However, sentiment is changing. The employer of labor is finding that rest and relaxation are essential to the greatest efficiency. Employees accomplish as much in a week of six days as they do in one of seven. The reduction in the hours of daily toil has not decreased the total efficiency.