The Cyrenaics or Kyrenaics (; Kyrenaïkoí) were a sensual hedonist Greek school of philosophy founded in the 4th century BCE, supposedly by Aristippus of Cyrene, although many of the principles of the school are believed to have been formalized by his grandson of the same name, Aristippus the Younger. The school was so called after Cyrene, the birthplace of Aristippus. It was one of the earliest Socratic schools. The Cyrenaics taught that the only intrinsic good is pleasure, which meant not just the absence of pain, (as it did for Epicurus) but positively enjoyable sensations. Of these, momentary pleasures, especially physical ones, are stronger than those of anticipation or memory. They did, however, recognize the value of social obligation and that pleasure could be gained from altruistic behaviour. The school died out within a century and was replaced by the philosophy of Epicureanism.