(Ewen; 2003; p. 42)
According to Freud, the mind is enriched with a fixed amount of psychic energy called "libido". Libido is also associated with sexual instincts. This libido when negate to grow furthermore in a child causes fixation, due to which in adulthood, the adult despite growing mentally continues with the same old habits which he used to adopt in childhood. "Because human nature is inherently malignant, we have no inborn wish to change for the better, and parents must pressure the reluctant child to proceed through the various stages of development. This task is fraught with difficulties, and some libido inevitably remains attached (fixated) to the pregenital erotogenic zones". (Nigel; 2001; p. 30)
"So long as most of the libido reaches the genital stage, no great harm is done. But if traumatic events occur during a pregenital stage, such as harsh attempts at weaning or overly severe punishment during toilet training, excessive amounts of libido become fixated at that stage. The child rejects further development, and demands the satisfactions that have been withheld. Excessive fixations can also be caused by overindulgence, as by allowing the child to engage in too much thumb sucking. Such intense gratification is undesirable because it is difficult to abandon and remains a source of yearning". (Nigel; 2001; p. 30)
Fixation may leave too little libido available ...