EUDAEMONISM, in ethics, the name applied to theories of morality which find the chief good of man in some form of hap piness (from Gr. Ev3acµovia, literally the state of being under the protection of a benign spirit, a "good genius"). The term eudae monia has been taken in a large number of senses, with conse quent variations in the meaning of eudaemonism. To Plato the "happiness" of all the members of a state, each according to his own capacity, was the final end of political development. Aristotle, as usual, adopted "eudaemonia" as the term which in popular language most nearly represented his idea and made it the key word of his ethical doctrine. None the less he greatly expanded the content of the word, until the popular idea was practically lost : if one be called Ebbaiµwv ("happy") he must have all his powers performing their functions freely in accordance with virtue, as well as a reasonable degree of material well-being; the highest conceivable good of man is the life of contemplation. Aristotle fur ther held that the good man in achieving virtue must experience pleasure (i) oH),which is, therefore, not the same as but the sequel to or concomitant of eudaemonia. Subsequent thinkers have to a greater or less degree identified the two ideas, and much confusion has resulted. Among the ancients the Epicureans expressed all eudaemonia in terms of pleasure. On the other hand attempts have been made to separate hedonism, as the search for a con tinuous series of physical pleasures, from eudaemonism, a con dition of enduring mental satisfaction. Such a distinction involves the assumptions that bodily pleasures are generally different from mental ones, and that there is in practice a clearly marked divid ing line—both of which hypotheses are frequently denied. Among modern writers, James Seth (Ethical Princ., 1894) resumes Aristotle's position, and places eudaemonism as the mean be tween the ethics of sensibility (hedonism) and the ethics of ra tionality, each of which overlooks the complex character of human life. The fundamental difficulty which confronts those who would distinguish between pleasure and eudaemonia is that all pleasure is ultimately a mental phenomenon, whether it be roused by food, music, doing a moral action or committing a theft. There is a marked disposition on the part of critics of hedonism to confuse "pleasure" with animal pleasure or "passion"—in other words, with a pleasure phenomenon in which the predominant feature is entire lack of self-control, whereas the word "pleasure" has strictly no such connotation. Pleasure is strictly nothing more than the state of being pleased, and it is purely arbitrary to con fine the word to those cases in which such stimuli are the proxi mate causes.