Aristotle · a new plain-English translation from the original language
1| BOOK 35. PROBLEMS CONCERNING THE OBJECTS OF TOUCH Why do we shudder more when someone else touches us in a certain way than when we touch ourselves in the same way? Is it because touch is more perceptive of what belongs to another than of what belongs to oneself? For what is organically continuous with us is imperceptible to itself. And what happens secretly and suddenly is more frightening, and fear is a kind of chilling; and another person's touch, as opposed to one's own, has both of these features. And in general, each thing is by nature affected either more, or only, by something else rather than by itself — as also happens in the case of being tickled. Why are the armpits and the soles of the feet ticklish? Is it because of the thinness of the skin there? And also because touch is unfamiliar there, as it is likewise with the ear? Why do we not all shudder at the same things? Is it because we do not all take pleasure in the same things either, just as we do not all feel pain at the same things? In the same way, then, we do not shudder at the same things; for shuddering is a certain kind of chilling. That is why some shudder when cloth is scraped between the teeth, others when a saw is being sharpened or drawn, others when pumice is being cut, and others when a donkey grinds a millstone.
2| Why, though summer is hot and winter cold, do people's bodies feel colder to the touch in summer than in winter? Is it because sweat and moisture chill the body, and this happens in summer but not in winter? Or is it because heat and cold exchange places in a manner opposite to the season, and heat flees inward in summer — which is also why it releases sweat — whereas in winter it shuts the cold out and the body gives off vapor, just as the earth does? Why does the hair on the skin bristle? Is it that, when the skin contracts, the hairs naturally stand up? And the skin contracts both from shivering and from other affections. Why does no one tickle himself? Is it because a person is also less ticklish when touched by another if he senses it beforehand, and more ticklish if he does not see it coming? So he will be least ticklish of all when he does not fail to notice that this is happening to him. Now laughter is a kind of derangement and deception. That is why people laugh when struck in the midriff; for it is not just any place that makes them laugh. And what is done in secret is deceptive. This is why laughter both occurs and, from one's own doing, does not occur.
3| Why is it that we are most ticklish on the lips? Is it because what is tickled must not be far from the organ of perception? And the lips lie especially close to that region. This is also why the lips are ticklish among the regions around the head, since they are well-fleshed, and are therefore the most easily moved of all. Why is it that, if someone scratches the region around the armpits, people burst out laughing, but not if he scratches some other place? Or again, why do people sneeze when they scratch their nostrils with a feather? Is it because there are places containing small veins, which, when they are either chilled or affected in the opposite way, either grow moist, or are dissolved from moisture into breath? Just as, if one presses the veins in the neck, people fall asleep. Now pleasure is a kind of warmth; and when more breath arises within us from this warmth, we release it all at once, outward. In the same way, too, in the case of sneezing, by warming the passage with the feather and scratching it, we dissolve the moisture into breath; and once it has become more, we drive it out. Why do we often shudder after eating? Is it because the cold things entering the body at the outset overpower the natural heat, rather than being overpowered by it? Why does an object rolled crosswise between the fingers appear to be two things? Is it because we are touching it with two organs of perception? For when the hand is held in its natural position, it is not possible for both inner surfaces of the fingers to touch it as a single thing at once.