In Freudian psychology, the pleasure principle is the psychoanalytic concept describing people seeking pleasure and avoiding suffering (pain) in order to satisfy their biological and psychological needs. Specifically, pleasure principle is a driven force of id.  Furthermore, the counterpart concept, the reality principle, describes people choosing to defer gratification of a desire when circumstantial reality disallows its immediate gratification. In infancy and early childhood, the id rules behavior by obeying only the pleasure principle. People in that age would only seek for immediate gratification in order to reduce their urges such as hunger, thirst or even sex. Maturity is learning to endure the pain of deferred gratification, when reality requires it; thus, the Psychoanalyst Sigmund Freud proposes that “an ego thus educated has become ‘reasonable’; it no longer lets itself be governed by the pleasure principle, but obeys the reality principle, which also, at bottom, seeks to obtain pleasure, but pleasure which is assured through taking account of reality, even though it is pleasure postponed and diminished
Sigmund Freud discusses this idea, pleasure principle, and its limits in more details in his book, Beyond the Pleasure Principle, published in 1921. In his discussion of the opposition between Eros, the life instinct, and the Thanatos, the death instinct, he examines the role of the repetition compulsion caused by the pleasure principle and of the sexual instincts.
In Freudian psychology, the reality principle is the psychoanalytic concept describing circumstantial reality compelling a man or a woman to defer (put off) instant gratification. The reality principle is the factual governor of the actions taken by the ego.
In infancy and early childhood, the Id rules behavior by obeying only the pleasure principle. Maturity is learning to endure the pain of deferred gratification, when...