The Divine Institutes

It is evident that there are many things in the body, the force and purpose of which no one can perceive but He who made them. Can any one suppose that he is able to relate what is the advantage, and what the effect, of that slight transparent membrane by which the stomach is netted over and covered? What the twofold resemblance of the kidneys? which Varro says are so named because streams of foul moisture arise from these; which is far from being the case, because, rising on either side of the spine, they are united, and are separated from the intestines. What is the use of the spleen? What of the liver? Organs which appear as it were to be made up of disordered blood. What of the very bitter moisture of the gall? What of the heart? unless we shall happen to think that they ought to be believed, who think that the affection of anger is placed in the gall, that of fear in the heart, of joy in the spleen. But they will have it that the office of the liver is, by its embrace and heat, to digest the food in the stomach; some think that the desires of the amorous passions are contained in the liver.

First of all, the acuteness of the human sense is unable to perceive these things, because their offices lie concealed; nor, when laid open, do they show their uses. For, if it were so, perhaps the more gentle animals would either have no gall at all, or less than the wild beasts; the more timid ones would have more heart, the more lustful would have more liver, the more playful more spleen. As, therefore, we perceive that we hear with our ears, that we see with our eyes, that we smell with our nostrils; so assuredly we should perceive that we are angry with the gall, that we desire with the liver, that we rejoice with the spleen. Since, therefore, we do not at all perceive from what part those affections come, it is possible that they may come from another source, and that those organs may have a different effect to that which we suppose. We cannot prove, however, that they who discuss these things speak falsely. But I think that all things which relate to the motions of the mind and soul, are of so obscure and profound a nature, that it is beyond the power of man to see through them clearly. This, however, ought to be sure and undoubted, that so many objects and so many organs have one and the same office—to retain the soul in the body. But what office is particularly assigned to each, who can know, except the Designer, to whom alone His own work is known?