If we acknowledge every little fact that has a bad effect upon our life, we give it life from our own, and thus make it a living thing. And so it is with many illnesses. Very often people get into the habit of saying, "Oh, I am so tired!" It is not necessary for them to cut wood or carry stones; they will be tired before doing it; no sooner do they think of tiredness than it is there. There are many cases in which there is no need to be tired; one becomes tired only by the fact of having acknowledged it. It is the same with sleeplessness. Once one acknowledges to oneself that one cannot sleep, that is enough to keep one awake all night. There are many illnesses of this kind, and chief among them is depression.