Aristotle's Problems

...that which is spread out and shines by itself reflects even more, transmitting its rays through the pores of the glass; it doubles what is on the surface and outside the glass body: and thus mirrors emerge in the manner of brightness.

Why do we behold ourselves in mirrors and clear waters? Because the quality of sight, passing out toward transparent bodies through the refraction of the rays that exit from the eyes, reaches the sight of itself. Nor is it a wonder that it should exceed the qualities of the face: thus, those who dwell among trees show a pale countenance, since the pale quality of the green leaves emanates into the face; likewise, passing into water or a pond, this influx makes the water itself appear green.

Why do clean caves and very high, purged places produce and send back the sound of the voice, and respond? For it soon strikes the air, and the air strikes the place; and the more the struck air strikes, the more vehement the sound happens to be produced. Moist places, however, being softer and yielding to the blows and loosening the sound itself, by no means produce it. But the blow is adapted to the quality and quantity of the voice, which is also struck in those qualities and quantities. It is falsely fabled that Echo—that is, the reverberated voice or the image of a voice—is a demon. There are those who say that Pan loved her, but falsely. For Pan was a wise man, who first desired and sought out the cause of the echo so that he might discern what it was; and just as all who are filled with desire are distressed when they do not achieve it, so he too was troubled before the solution. This is even as Endymion, who first investigated the course of the moon, staying awake at night following its course and seeking its movements, but sleeping by day; hence they fable that the moon loved him and came to him while he slept, when she rendered the solution of the cause to the philosopher. They say also that he was a shepherd, because he observed its movement through solitudes and pathless and very high places. He had a tablet, either because the blowing of the winds is greater around sublime places, or because he sought out the harmony of figures. Likewise Prometheus, since he was a certain wise man who sought the cause and nature and position of celestial aid, was consumed by a greed for learning and found rest only when Hercules resolved the things he had doubted by his own wisdom.

Why, when a stone is thrown into standing water on the surface and not onto deep ground, do many circles happen to break out from it? It must be said that by the force of the throw, the stone pursues the water everywhere from its body, and thus an equal circle is produced. Having a power equal to the force of the throw, the circle is even larger because of the immense force; for it reaches even to the ground, continually widening and following the water by that blow. It rightly then produces many circles of the body: first moving the interval of the circle on the surface of the water, then descending continuously to the bottom, and again dividing the water, it makes another; and this continues until it stays and rests. In the loosening of the force of the stone descending step by step, it happens that a thinner circle is made than the one that preceded it. Because of this, the water is likewise distinguished by the stone according to the blow.

Why do many think that laughter arises from the spleen, affirming that in contracted and rough spleens there are no such affections as are in robust ones, who say such men seem rather sad? It must be said that this is by accident, and not properly that the spleen is the cause of laughter. For when it is strong, it draws all the dreggy and melancholic juice from the liver, and thus sending pure blood into the whole body, it soothes the brain and delights nature, and affects the soul just as wine does and drives it to alacrity, whence laughter is excited.

Why do mules not reproduce? Because they consist of animals of different species, and from females different in temperament and nature. Therefore the mixture, being about to procreate something other than what existed before, destroys the nature of the procreators; just as the mixture of whiteness and blackness, destroying the extreme colors, produces another color—that is, dark brown—which is none of the extremes. Therefore the procreative temperament is destroyed, as well as the property of forms.

Why are those born deaf also mute? Because they cannot produce or speak what they have not heard. But some physicians say there is one conjugation of nerves that pertains to the tongue and the ears, so that those members must be affected together. Yet those who are deaf from some occurrence are not immediately also mute, for the nerve of hearing alone is affected. Similarly, those who are mute from an occurrence are not immediately deaf, for the disease is produced in its place in the nerves of the tongue.

Why do many who are fasting shiver after taking food? Because on account of the late taking of nourishment, the bilious accumulate a sharp humor; therefore after food, when the members have received strength and propel the bile from themselves to the skin, shivering happens to be produced as the bile stings the members and rises up to pursue them.

Why do swine keep silent if they are carried overturned and on their backs? Because besides other animals devoid of reason, these always look prone toward the ground, delighted by the stench which they seek; therefore, in the sudden change of sight, being caught and struck by much light, they are silent. But some say that having a narrow windpipe, the breathing passages collapse in the manner of a trapdoor.

Why mules do not reproduce.
Pliny: It is observed that from two different kinds, a third kind is born, and it is similar to neither of the parents; and those very ones that are so born do not procreate in any kind of animal. For this reason mules do not give birth; it is recorded in our annals that they have often given birth, but it was regarded as a portent. Theophrastus relates that they give birth in Cappadocia, but that the animal there is of its own kind.