tilings are true or that all things are false. For if certain things only are true < and others are false >, how are we to distinguish them ? Not by the senses, where things in the field of sense are in question, since all these things appear to sense to be on an equal footing ; nor by the mind, for the same reason. Yet apart from these faculties there is no other, so far as we can see, to help us to a judgement. Whoever therefore, they say, would be firmly assured about anything sensible or intelligible must first establish the received opinions about it ; for some have refuted one doctrine, others another. But things must be judged either by the sensible or by the intelligible, and both are disputed. Therefore it i^ impossible to pronounce judgement on opinions about sensibles or intelligibles ; and if the conflict in our thoughts compels us to disbelieve every one, the standard or measure, by which it is held that all things are exactly determined, will be destroyed, and we must deem every statement of equal value. Further, say they, our partner in an inquiry into a phenomenon is either to be trusted or not. If he is. he will have nothing to reply to the man to whom it appears to be the opposite a : for just as our friend who describes what appears to him is to be trusted, so is his opponent. If he is not to be trusted, he will actually be disbelieved when he describes what appears to him. We must not assume that what convinces us is actually true. For the same thing does not convince every one, nor even the same people always. Persuasiveness sometimes depends on external circumstances) on the reputation of the speaker, a e.g. to be not a serpent, hut a coil of rope.