Sextus Empiricus Pyrrhoniae Hypotyposes 3.29.264

[264] Neither can the so-called learner, if he is non- expert, learn and apprehend the principles of the art wherein he is non-expert. For just as the man who is blind from birth, in so far as he is blind, will not acquire perception of colours, nor, similarly, he who is deaf from birth, of sound, ¹ so too the non-expert will not apprehend the principles of the art wherein he is non-expert. For should he do so the same man would be both expert and non-expert in the same things—non-expert since he is such by hypothesis, and expert since he has apprehension of the principles of the art. Hence, neither does the expert teach the non-expert.