Aenesidemus (Greek: Αἰνησίδημος Ainēsidēmos) was a Greek sceptical philosopher, born in Knossos on the island of Crete. He lived in the 1st century BC, taught in Alexandria and flourished shortly after the life of Cicero. He was probably a member of Plato's Academy, but due to his rejection of their theories he revived the principle of epoché (εποχή), or suspended judgement, originally proposed by Pyrrho and Timon, as a solution to what he considered to be the insoluble problems of epistemology. His school is most commonly referred to as Pyrrhonism, but also as the third sceptic school. His chief work, the Pyrrhoneia (Πυρρώνειοι λóγοι) discussed four main ideas: the reasons for scepticism and doubt, arguments against causality and truth, a physical theory and an ethical theory. Of these, the former are the most significant and his reasons for the suspension of judgment were organized into ten "tropes", or modes. Very little is known about him as none of his works have survived, though he has been mentioned and discussed in detail by Photius (in his Myriobiblion) and Sextus Empiricus, and also to a lesser extent by Diogenes Laertius and Philo of Alexandria.