Chapter XXII.
Volatilia cur dicuntur volantia super terram secus firmamentum coeli. Atque ibidem de ea quae observatur in avibus, corporis diversitate. Postremo nonnulla de cygno et cicada subjunguntur.
73. Let us now consider what he says: Let the waters bring forth reptiles of living souls according to their kind, and flying creatures that fly above the earth according to their kind above the firmament of the sky. Why did he say 'above the earth'? It is certain because they seek their food from the earth. But how 'above the firmament of the sky' when eagles fly higher than other birds and yet they are not above the firmament of the sky? But because in Greek it is called οὐρανὸς, which we call 'coelum' in Latin: οὐρανὸς, however, comes from 'seeing', that is, from seeing, because the air is clear, and flying creatures were said to belong to the kinds of animals that fly in the air, which is purer for seeing. And do not be mistaken by what he says, here the term 'firmament' is not used properly, but metaphorically; because by comparing it to the ethereal body, even this air that we can perceive with our eyes, seems to have the role of a denser and thicker 'firmament'.
Now, because we have said what birds are, what nature and grace they have, and a few things about many; for we do not have the leisure to describe everything, since they are similar and of the same kind; nevertheless, let us consider the diversity that birds themselves have among themselves. For we find that the feet of a crow, for example, are separated and divided by certain distant and separated toes, and similarly the feet of ravens and chicks are also formed differently by nature; we observe that birds that feed on flesh are curved and bent, as if ready for prey. Indeed, those creatures that have the use and habit of swimming have broad feet, and their toes are connected by a certain membrane. In this, the admirable reason of nature is revealed; so that those creatures are able to catch or reach food through their adapted use, and these creatures have suitable aids for swimming, so that they can better float on the water, and with their feet, by the extension of that membrane, they propel themselves through the wider currents of the water as if with certain oars.
75. It is also evident why the swan uses its longer neck; because it is slightly slower in its body and cannot easily reach the depths of the water, it extends its neck to the prey, which it snatches as if it were a prelude to the other parts of the body's food that it has found, and pulls it out from the deep. Add to this that because of its longer and more melodious neck, it is distinguished by a higher and purer tone, and with longer practice it produces a much clearer sound.
76. How sweet is also the song in the small throat of the cicada, with which the bushes are burst in the middle of summer due to the more harmonious songs attracting purer air with their breath at that time, the more resounding are the songs. Nor do bees themselves sing anything unpleasant; for they have a pleasant sweetness in that hoarse murmuring of their voice, which we seem to imitate more slowly in the first broken sound of trumpets, nothing is considered more suitable for exciting the minds into vigor. And this gratitude remains for them, when it is revealed that they do not have the capacity or use of lungs for breathing; but they feed on airy respiration. Finally, if someone pours oil on them, they are quickly killed; because with the pores obstructed, they cannot draw in that airy respiration: and if someone immediately pours vinegar on them, they revive, because the force of the vinegar quickly carries moisture to open the pores, which are blocked by the concretion of oil.