  There is one more twist in the story, however. After removing to Rome, Philo published a pair of books – the so-called Roman Books – which, when they came to Antiochus’ attention in Alexandria, seemed to him to represent a radical and intellectually untenable departure from his teacher’s previous position. This was the occasion for the Sosus, which contained a stinging riposte to Philo’s new ideas. In opposition to Antiochus’ view that there were two Academies, an Old and a New, Philo maintained that there had only ever been one. But he now held that the Academics from Plato to Philo himself were not united by their skepticism, as we have seen some Academics believed. Rather they had never been skeptics because they had never meant to challenge the possibility of knowledge. Philo did not deny that Arcesilaus and Carneades had argued against the existence of cognitive impressions. Rather, he now maintained that these arguments showed, and were always intended to show, not that cognition or apprehension is impossible, but that it is impossible on the Stoic conception of apprehension, which is therefore mistaken (Acad. 2.18; S.E. PH 1.235).