 Cicero suggests that even the Stoic sage will follow many things on the basis of plausibility, if life is to be possible at all (2.99); and his point, I take it, is supposed to apply not just in case it turns out that there are no cataleptic impressions, but even in those (presumably frequent) situations where such impressions, should they exist, are not present. The wise still have to live. Indeed, if one includes the crucial refinement made by the leading sceptical philosopher Carneades as part of the plausibility criterion – namely that the impression must be ‘unimpeded’ (2.104) – then we seem to have a way of addressing Lucullus’ point that to have a notion of plausibility, or being likely to be true, depends on one’s having a prior notion of truth as such.