The place of the will in its influence upon health and vitality has long been recognized, not only by psychologists and those who pay special attention to problems of mental healing, but also, as a rule, by physicians and even by the general public. It is, for instance, a well-established practice, when two older folk, near relatives, are ill at the same time, or even when two younger persons are injured together and one of them dies, or perhaps has a serious turn for the worse, carefully to keep all knowledge of it from the other one.