The roots of internalization and identification establish themselves in the infant's concrete physical ties to the mother. These ties are provided by the early basic processes which constitute child care and it is these which set the pattern for later experiences that lead to individuation.

Sucking at the breast is to be seen as the basic pattern of reunion after the separation of birth; by it the infant re-establishes continuity. In the breast's absence, nipple substitutes are used to satisfy the infant's need for contact, which means continuity—non-nutritional sucking. Nipple substitutes are called by the author precursors, (P.O.s) meaning that they precede symbolic representation.