When he came to Athens he was a hearer of Antiochus of Ascalon, with whose fluency and elegance of diction he was much taken, although he did not approve of his innovations in doctrine. For Antiochus had now fallen off from the New Academy, as they call it, and forsaken the sect of Carneades, whether that he was moved by the argument of manifestness and the senses, or, as some say, had been led by feelings of rivalry and opposition to the followers of Clitomachus and Philo to change his opinions, and in most things to embrace the doctrine of the Stoics. But Cicero rather affected and adhered to the doctrines of the New Academy; and purposed with himself, if he should be disappointed of any employment in the commonwealth, to retire hither from pleading and political affairs, and to pass his life with quiet in the study of philosophy.
Plutarch, Life of Cicero (tr. by John Dryden). I've mentioned both the New Academics and Antiochus's break from them before. What I really like about the passage is the disjunctive explanation for Antiochus's break and development of a new Stoicism-Platonism mix: either (1) he was convinced by the Stoic argument that there were certainly true sense perceptions and therefore broke with the New Academy or (2) he came to accept the argument because he got angry at opponents in the internal politics of the New Academy and broke with it entirely. That's the way philosophy works in the human world.