According to Sigmund Freud, the loss of the object is a two-step process whereby the subject is constituted. First, the earliest partial object, the breast, is lost. Then the primary love object, the mother, is likewise lost.
The earliest sexual object is the breast, and the earliest source of satisfaction for the sexual instinct is the encounter between two partial objects, the infant's mouth and the mother's breast. In Three Essays on the Theory of Sexuality (1905d), Freud explained that the breast becomes a lost object "just at..