Love and hate (psychoanalysis)  Love and hate as co-existing forces have been thoroughly explored within the literature of psychoanalysis, building on awareness of their co-existence in Western culture reaching back to the “odi et amo” of Catullus, and Plato's "Symposium". Ambivalence was the term borrowed by Sigmund Freud to indicate the simultaneous presence of love and hate towards the same object. While the roots of ambivalence can be traced back to breast-feeding in the oral stage, it was re-inforced during toilet-training as well. Freudian followers such as Karl Abraham and Erik H. Erikson distinguished between an early sub-stage with no ambivalence at all towards the mother's breast, and a later oral-sadistic sub-phase where the biting activity emerges and the phenomenon of ambivalence appears for the first time. The child is interested in both libidinal and aggressive gratifications, and the mother's breast is at the same time loved and hated. While during the pre-oedipal stages ambivalent feelings are expressed in a dyadic relationship between the mother and the child, during the oedipal conflict ambivalence is experienced for the first time within a triangular context which involves the child, the mother and the father. In this stage, both the boy and the girl develop negative feelings of jealousy, hostility and rivalry toward the parent of the same sex, but with different mechanisms for the two sexes. The boy's attachment to his mother becomes stronger, and he starts developing negative feelings of rivalry and hostility toward the father. The boy wishes to destroy the father so that he can become his mother's unique love object. On the other hand, the girl starts a love relationship with her father. The mother is seen by the girl as a competitor for the father's love and so the girl starts feeling hostility and jealousy towards her. The negative feelings which arise in this phase coexist with love and affection toward the parent of the same sex and result in an ambivalence which is expressed in feelings, behavior and fantasies. The negative feelings are a source of anxiety for the child who is afraid that the parent of the same sex would take revenge on him/her. In order to lessen the anxiety, the child activates the defense mechanism of identification, and identifies with the parent of the same sex. This process leads to the formation of the Super-Ego. According to Freud, ambivalence is the precondition for melancholia, together with loss of a loved object, oral regression and discharge of the aggression toward the self.