Carried to the extreme, regression leads one in type of thinking and in ideas back to childhood and earliest infancy. The final goal is a state of mental vacuity such as probably characterizes the infant at the time of birth and during the first days of extra-uterine life. In this state what interest there is, is directed entirely to the physical comfort of the individual himself, and contact with the environment is so undeveloped that efforts to obtain from it the primitive wants of warmth and nutrition are confined to vague instinctive cries. Evolution to true contact with the world around implies effort, the exercise of self-control, and also self-sacrifice, since the child soon learns that some kind of _quid pro quo_ must be given. Viewed from the adult standpoint, the emptiness of this early mental state must seem like the Nirvana of death. At least death is the only simple term we can use to represent such a complete loss of our habitual mental functions. When life is difficult, we naturally tend to seek death. Were it not for the powerful instinct of self-preservation, suicide would probably be the universal mode of solving our problems. As it is, we reach a compromise, such as that of sleep, in which contact with reality is temporarily abandoned. In so far as sleep is psychologically determined, it is a regressive phenomenon. It is interesting that the most frequent euphemism or metaphor for death is sleep. Sleep is a normal regression. It does not always give the unstable individual sufficient relaxation from the demands of adaptation and so pathological regressions take place, one of which we believe stupor to be. It is important to note that objectively the resemblance between sleep and stupor is striking. So far as mental activity in either state can be discovered by the observer, either the sleeper or the patient in stupor might be dead. Briefly stated, then, our hypothesis of the psychological determination of stupor is that the abnormal individual turns to it as a release from mental anguish, just as the normal human being seeks relief in his bed from physical and mental fatigue. When this desire for refuge takes the shape of a formulated idea, there are delusions of death.