This paper is a corroboration of the suggestion by Jekels and Bergler in Instinct Dualism in Dreams that sleep is an expression of the death impulse (Thanatos). Eros is the counterforce which, by mobilizing a powerful libidinal investment including the infantile sexual wishes, prevents Thanatos from overwhelming the ego. As evidence supporting this, Róheim draws on dream material and on many beliefs among primitives regarding the departure of the soul from the body during sleep and the hazards to the sleeper should the soul have difficulty reëntering the sleeping body.