What can the reason be that we all, though deceived by the same means and through the same persons, cannot yet give over folly?
For this sort of fraud had been practised often and by many.
It is perhaps not surprising that it succeeds with others, but it is indeed astonishing that it does so with those who are the very fount of such trickery.
The reason however is that we do not bear in mind Epicharmus's excellent advice,"Be sober and mindful to mistrust; these are the thews of the mind."
Walbank Commentary