The Truth of the Senses

Next we come to the question of how far those five senses can be trusted — the ones we are taught to count off along with our alphabet — since even here the heretics find something to prop up their case. They are sight, hearing, smell, taste, and touch. The Academy attacks their reliability far too harshly, and some say Heraclitus did the same, and Diocles, and Empedocles. Plato at any rate, in the Timaeus, declares that what the senses do is irrational, and tangled up with our opinions and beliefs. [a]

Sight is charged with deception. It reports that oars are bent or crooked once they go into the water, though we know for certain that they are straight. It reports that a distant tower with square corners is round. It denies that the two sides of a colonnade run parallel, and makes them narrow more and more toward the far end. And it joins the sky to the sea, though the sky hangs at such a height above it. Hearing is charged with the same fault. We take for a noise in the sky what is really nothing but a cart rumbling past; or, if you would rather have it the other way around, we were quite sure a cart was making the noise when thunder was rolling in the distance. Smell and taste are said to be at fault as well, because the same perfume and the same wine lose their value once we have been with them a while. Touch is blamed on the same grounds: the very pavement that felt rough to the hands is smooth enough to the feet, and in the baths a stream of warm water is pronounced scalding at first and beautifully mild afterward. So, on their account, our senses deceive us — when all the while it is we who are shifting our opinions.

The Stoics take a more moderate line. They do not load every sense, on every occasion, with the reproach of deception. The Epicureans are more consistent still: they hold that all the senses report truly, and always do, only in different ways. It is not our organs of sensation that are at fault, but our opinion. The senses only sense; they do not form opinions. It is the soul that forms an opinion. So they separated opinion from the senses, and sensation from the soul. Well then — where does opinion come from, if not from the senses? Unless the eye had made out a round shape on that tower, the mind could never have got the idea that it had roundness. And where does sensation come from, if not from the soul? For if the soul had no body, it would have no sensation. So sensation comes from the soul, and opinion from sensation, and the whole business is the soul.

But there is more to be pressed here. Something causes the gap between what the senses report and how the facts actually stand. Since it is possible, as we have seen, for appearances to be reported that do not exist in the objects, why should it not be equally possible for appearances to be reported that are produced not by the senses but by conditions that come in between, in the very nature of the case? If that is so, it is only right that those conditions be given their due. The truth is that the water was the cause of the oar’s looking bent or crooked; out of the water it looked perfectly straight, which is also what it was. A substance fine enough to act as a mirror by its own brightness will, when it is struck or shaken, destroy by that vibration the look of a straight line. In the same way, the state of the open air that fills the space between us and the tower is bound to hide the tower’s true shape; the surrounding air, of one uniform density, covers the corners with the same light and rubs out their outlines. So too the colonnade, of one width all along, is pared away toward its far end, until under its long roof it looks narrower and narrower and finally comes to a vanishing point at the limit of sight. So too the sky blends itself into the sea: the eye is spent at last, though while its glance held its strength it kept the boundary of the two elements exactly. As for the alleged cases of deceptive hearing, what else could have produced the illusion but the likeness of the sounds? And if the perfume was weaker to the nose afterward, and the wine flatter to the tongue, and the water less hot to the touch, their original strength was still there in all of them, pretty well unimpaired. As for the pavement, rough and smooth at once, it was only natural and right that limbs as different in tenderness and hard skin as the hands and the feet should take different impressions from it. In this way, then, there can be no illusion in our senses without an adequate cause.

Now if particular causes like these mislead our senses, and through our senses our opinions too, then we must no longer put the deception down to the senses, which are only following the specific causes of the illusion, nor to the opinions we form, since those are set going and steered by the senses, which are following the causes. People afflicted with madness or derangement mistake one thing for another. Orestes sees his mother in his sister; Ajax sees Ulysses in the slaughtered herd; Athamas and Agave make out wild animals in their own children. Is it their eyes you must blame for so enormous a mistake, or their frenzy? To men with jaundice everything tastes bitter, from the excess of bile in them. Will you charge their sense of taste with the lie, or their bad health? All the senses, then, are thrown out of order now and then, or imposed upon — but only in a way that leaves them entirely blameless in the work that is natural to them.

Nor, going further still, must we bring an indictment of deception even against those specific causes and conditions themselves. These departures from the ordinary happen for stated reasons, and reasons do not deserve to be counted as deceptions. Whatever ought to happen in a certain way is not a deception. If, then, even these attendant causes must be acquitted of all censure and blame, how much more should we clear the senses of reproach, over which those causes hold so free a sway? We are bound, therefore, most certainly to claim for the senses truth, and faithfulness, and integrity — since they never render any other account of what strikes them than the one required of them by the specific causes and conditions which in every case produce the discrepancy between what the senses report and how the objects actually are.

What do you mean by it, then, most insolent Academy? You overthrow the entire condition of human life. You throw the whole order of nature into confusion. You cast a shadow on the good providence of God himself — for the senses of a human being, which God set over all his works so that we might understand them, live in them, manage them and enjoy them, you call lying and treacherous tyrants! But is it not through them that the whole creation receives our labor? Is it not by their means that a second shape is stamped even upon the world — so many arts, so many resourceful trades, so many pursuits, so much business, so many public duties, so much commerce, so many remedies, plans, comforts, ways of living, refinements and accomplishments of life? All these are what have given human existence its relish and its savor. And it is by these senses of his that a human being, alone of all living things, has the distinction of being a rational animal, with a capacity for understanding and knowledge — able, in fact, even to found the Academy itself. But Plato, in order to run down the testimony of the senses, in the Phaedrus makes Socrates deny that he is able even to know himself, as the Delphic oracle ordered; in the Theaetetus he strips himself of the powers of knowing and of sensing; and again in the Phaedrus he puts off until after death the knowledge of the truth — “posthumous knowledge,” as he calls it. And for all that, he went on playing the philosopher before he died.

We may not — I say we may not — call the truth of these much-abused senses into question, or we will end by bringing the truth of Christ’s own sensation into doubt. It might be said that he did not really “see Satan fall like lightning from heaven”; that he did not really hear the Father’s voice bearing witness to him; that he was deceived when he touched Peter’s mother-in-law; that the fragrance of the ointment he smelled afterward was not the fragrance he accepted for his burial; that the taste of the wine was not the taste of what he set apart in memory of his blood. It was on this false principle that Marcion actually chose to believe that he was a phantom, refusing him the reality of a complete body. But not even to his apostles was his nature ever a matter of deception. He was truly seen and heard on the mountain. True and real was the draught of wine at the wedding in Cana of Galilee. True and real also was the touch of Thomas, once he believed. Read what John testifies: “What we have seen, what we have heard, what we have looked at with our own eyes, and our hands have handled, concerning the Word of life.” That testimony would of course be false, and deceptive, if the witness of our eyes and our ears and our hands were by nature a lie.