If anyone thinks that nothing is known, he does not know whether this proposition can be known either, since he admits that he knows nothing. It seems, therefore, rather pointless to argue at all with someone who is standing on his head. Nevertheless, suppose I were to grant that he does know this, then I shall go on to ask him this one question: since up to now he has never seen any truth in things, how does he know the difference between knowing and not knowing in particular instances? What was it that gave him the concept of the true and the false? What evidence was there for drawing a distinction between what is doubtful and what is certain? You will find that the concepts of the true come in the first place from the senses, and that the evidence of the senses cannot be overthrown. To do so one must find some other standard of greater authority, able of itself to convict falsehood by asserting truth. But what can be considered of greater authority than the senses? Shall we say that reason, based on a deceptive sense — impression, is strong enough to contradict the senses, when reason itself is wholly based on the senses? If the senses are not true, then how can there be any truth in reason either? Or can hearing challenge the evidence of sight, or touch that of hearing? Will the tongue's taste argue against the touch, will the nose prove it wrong, will the eyes bring a contrary verdict? The answer, I think, is "no." For each has its own particular function and its own power. It is therefore necessary to use a particular sense in order to decide what is soft, or what is cold or hot, and another particular sense to perceive the various colors of things and to see what is involved in color i.e., shape. —Rex Warner . . . It follows that one sense cannot prove another sense wrong. Nor can the same sense convict itself of falsehood, since we must always give equal credit to every sense impression. What at any time has appeared to be true to the senses, is true. And if reason does prove unable to explain the cause why objects which were square when close at hand seem to be rounded when looked at from a distance, nevertheless it is much better with one's faulty reason to give an inaccurate explanation of these shapes than at any point to lose one's grip on what is absolutely obvious, to break faith with what is our first authority for everything and to tear up the entire foundation on which life and existence rest. Not only would the whole structure of reason collapse; life itself too would immediately disintegrate unless you have the courage to believe in the senses. . . .