In the human species it is probably true that dreaming is present from early childhood to the time of death. Some writers believe that infants do not dream; Aristotle thought that dreaming was abeyant prior to the fourth or fifth year, Perez,1 on the other hand, regards dreaming as present as early as the third month. He says, in speaking of a child's imagination: "How can we otherwise explain a child's dreams, the sudden tremblings, the screams, the sobs, the smiles, the movements to seize hold of an object or to repel it violently, which we observe in an infant of three months while asleep, and which resemble the actions produced during its waking hours by fear, pain, hunger, desire and joy?" The same author believes that according to the nature of the dreams at night the child is more or less cheerful during the day and inclined to be good and obedient.

Ordinary observation will show that infants laugh, moan, make sucking movements during sleep; when they smile the mothers say the angels are whispering to them. These signs are disregarded by many as being inadequate proof of dreaming; it is contended that sucking movements have been observed when the infant was awake and when there was no relation between the action and mental processes, the act being considered an instinct. Startled awakenings would be attributed to some physical, painful stimulus.

1 The First Three Tears of Childhood, English Translation, 1888, pp. 147 and 55.

If we are to judge from the actions of idiots - whose mentality is comparable to that of infants or young children - dreaming begins in early life, though, naturally, the younger the child the more fragmentary the dreams. The writer has observed sleeping idiots laugh, move their lips as if tasting some delicious morsel, cover their faces with their hands, as if protecting themselves from injury, etc.

In old age the dreams become of a distinctly retrospective character. This is particularly true of those who no longer take an active interest in the world's work. Dreams are reminiscent at all times, but in the old they are, more than in middle life, concerned with the pleasurable incidents of childhood and early manhood.