The problem of sleep is, of course, bound up with the physiology of rest, and as recuperation, in a physical sense, necessitates temporary cessation of function, so in the mental sphere we see that relaxation is necessary if our mental operations are to be carried on with continued success. This is probably the teleological meaning of sleep in its psychological aspects, for in it we abandon diurnal adaptive thinking and retire to a world of fancy, very often solving our problems by “sleeping over them.” The innate desire for rest and a fresh start is almost as fundamental a human craving as is the tendency to seek release in death. In fact the two are closely associated both in literature and in daily speech, for in many phases we correlate death with new life. If one is to visualize or incorporate the conception of new life in one term, rebirth is the only one which will do it, just as death is the only word which epitomizes the idea of complete cessation of effort. Not unnaturally, therefore, we find in the mythology of our race, in our dreams and in the speech of our insane patients, a frequent correlation of these two ideas, whether it comes in the crude imagery of physical rebirth or projected in fantasies of destruction and rebuilding of the world. Many of our psychotic patients achieve in fancy that for which the Persian poet yearned: “Ah Love! could you and I with Him conspire To grasp this Sorry Scheme of Things entire, Would we not shatter it to bits--and then Re-mold it nearer to the Heart’s Desire!” A vision of a new world is a content occurring not infrequently in manic states, but before the universe can be remolded it must be destroyed. Before the individual can enjoy new life, a new birth, he must die, and stupor often marks this death phase of a dominant rebirth fantasy. In this connection it was not without significance to note that stupors almost universally recover by way of attenuation of the stupor symptoms, or in a hypomanic phase where there seems to be an abnormal supply of energy. Antæus-like, they rise with fresh vigor from the Earth. They do not pass into depressions or anxieties. Rebirth fancies unquestionably, then, contain constructive and progressive elements, but, as has been stated above, any thinking which implies a lapse of contact with the environment is, in so far as that lapse is concerned, regressive, and in consequence rebirth fancies, as dramatized by the stupor patients, are regressive, just as are the delusions of death itself.