Motivation in psychology.
D004328:Drive; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D006706:Homeostasis; D006801:Humans; D007323:Instinct; D009042:Motivation; D010684:Philosophy / Q000266:history; D011574:Psychoanalytic Theory; D011584:Psychology / Q000266:history