After listing the propositions that must be considered as basic, the author formulates a theory of human motivation in line with these propositions and with the known facts derived from observation and experiment. There are 5 sets of goals (basic needs) which are related to each other and are arranged in a hierarchy of prepotency. When the most prepotent goal is realized, the next higher need emerges. "Thus man is a perpetually wanting animal." Thwarting, actual or imminent, of these basic needs provides a psychological threat that leads to psychopathy.