He was one of three philosophers sent to Rome in 155 BC (the other two being Carneades and Diogenes of Babylon), where their doctrines fascinated the citizens, but frightened the more conservative statesmen.
He was born in Phaselis, a Greek colony in Lycia, c. 200 BC, and studied philosophy at Athens under Aristo of Ceos, and became one of the leaders of the Peripatetic school by his eminence as an orator, a scholar and a moralist.
The novelty of their doctrines seemed to the Romans of the old school to be fraught with such danger to the morals of the citizens, that Cato induced the senate to send them away from Rome as quickly as possible.
By the time Licinius Crassus arrived at Athens c. 111 BC, he found Critolaus' pupil Diodorus of Tyre at the head of the Peripatetic school.
[2] A Critolaus is mentioned by Plutarch[9] as the author of a work on Epirus, and of another entitled Phenomena; and Aulus Gellius[10] also speaks of an historical writer of this name.