“It would be in contradiction to the conservative nature of the drives if the goal of life were a state of things which had never yet been attained. On the contrary, it must be an old state of things, an initial state from which the living entity has at one time or another departed and to which it is striving to return by the mazings along which its development leads. …For a long time, perhaps, living substance was thus being constantly created afresh and easily dying, till decisive external influences altered in such a way as to make ever more complicated mazings before reaching its aim of death. These mazings to death, faithfully kept to by the conservative drives, would thus present us today with the picture of the phenomena of life.”
Sigmund Freud, Beyond the Pleasure Principle