<Tr> <Td> Key concepts (show) <Ul> <Li> Aponia </Li> <Li> Ataraxia </Li> <Li> Eudaimonia </Li> <Li> Happiness </Li> <Li> Hedone </Li> <Li> Pain </Li> <Li> Pleasure </Li> <Li> Sensation </Li> <Li> Suffering </Li> <Li> Tetrapharmakos </Li> </Ul> </Td> </Tr> <Ul> <Li> Aponia </Li> <Li> Ataraxia </Li> <Li> Eudaimonia </Li> <Li> Happiness </Li> <Li> Hedone </Li> <Li> Pain </Li> <Li> Pleasure </Li> <Li> Sensation </Li> <Li> Suffering </Li> <Li> Tetrapharmakos </Li> </Ul> <Tr> <Td> Related articles (show) <Ul> <Li> Paradox of hedonism </Li> <Li> Hedonic treadmill </Li> </Ul> </Td> </Tr> <Ul> <Li> Paradox of hedonism </Li> <Li> Hedonic treadmill </Li> </Ul>

Who were the philosophers and what did they believe