Lucian Fugitivi 15

[15] Moreover, they discerned, I assume, the further advantage that they would be on an equal footing with true philosophers, and that there would be nobody who could pass judgment and draw distinctions in such matters, if only the externals were similar. For, to begin with, they do not even tolerate investigation if you question them ever so temperately and concisely; at once they begin shouting and take refuge in their peculiar citadel, abusiveness and a ready staff. Also, if you ask about their works, their words are copious, and if you wish to judge them by their words, they want you to consider their lives.

[15] They foresee, of course, that they will be on the same footing as genuine philosophers; so long as their exterior is conformable, no one is likely to make critical distinctions. They take care not to risk exposure: at the first hint of a rational argument, they shout their opponent down, withdraw into the stronghold of personal abuse, and flourish their ever-ready cudgels. Question their practice, and you will hear much of their principles: offer to examine those principles, and you are referred to their conduct.