The term Eudaemonia has been taken in a large number of senses, with consequent variations in the meaning of Eudaemonism.
Aristotle, as usual, adopted "eudaemonia" as the term which in popular language most nearly represented his idea and made it the keyword of his ethical doctrine.
Among the ancients the Epicureans expressed all eudaemonia in terms of pleasure.
The fundametal 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.
Aristotle further held that the good man in achieving virtue must experience pleasure (iiSov17), which is, therefore, not the same as, but the sequel to or concomitant of eudaemonia.