David had much reason to exclaim and confess so many times that God was admirable in all his works, however small they may appear. I say this because we now leave one
marvel, and enter into another no lesser one, which is the fabric of our eyes, which the professors of this science confess to be the most artful, most subtle, and most admirable thing of as many as the Creator formed in our bodies, in which, just as in the past one, the benefit is no less than the marvel of the work. For what thing is sadder than a man without sight?, since holy Tobias, who with so much patience suffered the lack of it, when the angel greeted him, and said to him that God should give him joy, responded: “What joy can I have, living in darkness and not seeing the light of heaven?” Then, having now treated of the parts of our body that are hidden within the veil of our flesh, now it will be reason to treat of the exterior senses and members of our body, which are on the frontier of our house in view of all, and we shall begin with the most excellent of the exterior senses, which are the eyes, and thus the artifice and fabric of them surpasses that of all the other members and senses.
And the first thing that ought to put us in admiration is the species and images of things that are required in order to see them. For which it is to be known that all visible things, which are those that have color or light, produce from themselves in the air their images and figures, which the philosophers call species, which very properly represent the same things whose images they are. The reason for this is because, according to rules of philosophy, the causes that produce some effect must touch one another, either by their own substance, or by some virtue or influence of theirs. And since here we treat of this effect, which is to see things, and they are apart from our sight, it is necessary that they touch and join by some third thing. And for this the Creator provided a thing worthy of admiration, which is that all visible things produce in the air these images and species that reach our eyes, and represent the same things that have to be seen. Which is seen in a mirror, which receiving in itself these species and images, and they not being able to pass onward because this mirror is not transparent, stop there, and it represents to us most perfectly all that they have before them. And thus in them we see mountains, and valleys, and fields, and trees, and entire armies, with all the rest that they have present, and if there were a thousand mirrors divided through all the air, in all of them the same thing would be represented. And not only in the air, but also in the heaven, what has been said has place, because we could not see the stars being so apart from our sight, if they did not impress their species and images in our eyes, so that by means of them they might be seen. Then what thing is more admirable than that, seeing how a painter spends many days finishing an image, each one of these visible things should be powerful to produce without brush and without ink and without space of time such infinity of images with all transparent bodies, as are the air and the heaven? Who does not see here the omnipotence of him who could give such virtue to all visible things so that they could be seen?
But treating of the organ of sight, it is to be known that from that front part of our brains, where we said the common sense was, two nerves are born, one on one side, and another on the other, through which those spirits that we call animal descend to the eyes, and these give them virtue to see, being first themselves informed with those species and images of things that we said. But of the fabric of these eyes there are written things so delicate and admirable that I do not attain them, and still less will I be able to write them. But the one that seems to me most admirable of all is that, with there being so many and so admirable things that are required for this fabric of the eyes, that sovereign Artificer was powerful to
place them in the head of the ants. Then how much greater marvel is this than to have placed the eyes in the head of man or of some elephant?
But while keeping silent about other more subtle things I shall not fail to say that in the composition of the eye there enter three differences of humors, which are divided among themselves with three most delicate webs. And the first of them they call crystalline, because it is solid and transparent as crystal is. And after this there follows another red humor, which is shelter and boundary of the crystalline, and after this there follows another blue one. And this color serves so that, by virtue of it, those species and images that we said may be gathered and fortified in the pupil of the eye, which would be offended by much brightness, as it is offended when we look at the sun.
Then through these glass-panes of the aforesaid humors, if they can be so called, the species and images of things enter, and rise by the aforesaid nerves to the common sense that we said, from which they are born. So that through them descend the animal spirits that make us see, and through these same ones the images of things ascend to this aforesaid little ventricle of the common sense, and from there they travel to the other interiors. And according to this we can say that the whole visible world, as great as it is, enters into our soul by this door of the eyes. And this is the cause, as Aristotle says, of this sense being so prized, because as man, being a rational creature, naturally desires to know, and this sense of sight discovers to him infinite differences of things, from here comes to him prizing this sense much. But it has another thing more excellent, which is to see by it the marvels of the works of God, whereby our spirit rises to the knowledge of him. Thus David shows it when he says: “I shall see, Lord, your heavens, which are works of your hands, and the moon and the stars that you founded.” This holy man employed the benefit of sight better than those who use it for offense of him who gave it to them, making matter of sin what ought to have been of his praises, and making war against the giver with the same gift that he gave them, and more such a gift as this is. For if a man should lose this, what would he do? Where would he not go to seek the remedy? And what thanks would he give to whoever should give it to him? And with this being so, and men knowing that God is the one who gave them sight, and the one who conserves it for them, it does not pass through their thought to give him thanks for it.
Let us pass from the sense of seeing to that of hearing, which is also a noble sense, and no less helps wisdom, of which we have example in Didymus, who was born blind, and did not for that reason fail to be a great theologian. Then of this sense two nerves are cause, which proceed from the common sense, one on one side and another on the other, which carry with themselves the animal spirits that give us virtue to hear. But within the ears there is a little bladder that they call myringa, full of air, which is like a little drum, and the sound of the voice, or of any other thing, arriving there, strikes this organ, and with this hearing is caused. But if this little bladder by some occasion is broken and the air goes out from it, hearing is then lost, and for this cause the Creator formed the ears, just as the eyelids in the eyes, for guard of this sense.
The same origin has the sense of smelling, to which descend two other nerves that proceed from the same fountain of the common sense and arrive at the noses, which have within themselves two little nipples of very soft and spongy flesh wrapped in some delicate webs, where the aforesaid nerves come to stop, and the air arriving here that carries with itself the species of fragrant things, smelling them is caused.
And for guard of this sense the Creator provided the noses, which also serve for beauty of the face, because what would a man without noses seem? Where it is much to note the infinite wisdom of the Creator, who joined in the fabric of all our senses and members two things most difficult to couple in one, which are utility and beauty, tracing things in such manner that the most profitable for life should also be most beautiful for sight.
The noses also serve, with the two holes that they have, so that not only by the mouth, but also by them, the phlegm that is bred in the brain may be purged, because as the vapors of our body rise to the high part of the head, as those of the earth rise to the high part of the air, the Creator provided these two drains, by which this evil humor might be purged. And still another thing intervenes here more admirable, because in the lowest part of the head there is a funnel that nature fabricated, which has the cup wide and round, and comes to finish in a narrow pipe, and this funnel gathers the phlegms that are distilled from the whole head, and by this narrow pipe they come to stop at these two aforesaid drains, so that, just as in the courtyards of great houses there is a sink, to which the waters run when it rains, so the Creator provided in this our house this sink, by which the phlegms are sent away, so that they may not do us harm. In which we see how in nothing did the Creator neglect what was fitting for our health and life.
From here let us descend a little lower to the sense of taste, with which we taste flavors, the sweet and the bitter, the savory and the insipid. And the cause of this feeling is two nerves that are in the middle of the tongue, and branch and extend through all of it, which the Creator provided should be moist, and full of pores, and empty of every kind of flavors. And the cause of its being full of pores is so that the species of flavors may be able to enter through it, and arrive at these aforesaid nerves, which are the cause of this taste. It was also fitting that it should be moist, to moisten the foods, because it could not feel the flavor of them without the moisture of the saliva. And it was no less fitting that it should lack all flavor, just as the organ of hearing lacks all sound, so that it could perceive all the differences of flavors. For if it had some within itself, it would feel only this, and not the others, as happens to him who has choleric fevers, to whom all things taste bitter by reason of the choleric humor with which the tongue is infected, which of itself is bitter. But here it is to be noted a difference that there is between this sense and the others, which is that the species of things that have to be seen, heard, and smelled have to pass through some transparent body, as is the air, but neither in this sense nor in the one that follows does this have place, because what has to be tasted or touched has to be joined with our flesh, so that the savory thing has to join itself with our tongue so that its flavor may be felt. In which is seen how brief this delight is, since as a doctor says, the delight of gluttony in space of time is scarcely of four moments, and in space of place is not even of four fingers and, this being so, we see how many rents and patrimonies are spent in serving this delight. For which Seneca exclaimed, saying: “O good God, how many kinds of officers and of offices one single belly keeps occupied!”
The last sense is touch, with which we feel the four first qualities of the elements, which are cold and heat, moisture and dryness, and we also feel the hard and the soft, the rough and the smooth. This sense does not have a marked place in our body where it is situated, because it is extended through all of it, because it is thus necessary so that the animal may feel the harmful and the profitable, and thus flee the one, and seek the other. And the cause of this feeling is another lineage of nerves that are poured through all the body, and are cause of sense, just as there are others that are so of movement, according as has already been declared. To this that up to here has been said, I shall add what Tully says on this matter.