Greenacre describes the effect of early physical determinants on the development of the sense of identity, especially the effect of awareness of one's genitals, face, and body from on the development of the body image, which is basic to the beginning of the sense of reality. The core on which identity is built is the inner awareness of one's own form and functioning, the inner structure and organization of the body. The sense of identity is influenced by awareness of external attributes of the outer surface of the body and involves repeated comparisons and contrasts with others. The sense of identity comes into being in the anal phase, though it is more fully developed in the phallic Oedipal period,