Another more perfect degree of life have animals (chiefly those that we call perfect) than plants, of which until here we have treated, because they have sense and movement, and as much as these are more perfect than plants, so much greater notice do they give us of the Creator, who has greater providence for the more perfect things. And thus there are books by great authors, and even by illustrious kings, who, marveling at the fabric of the bodies of animals, and much more at the abilities that they have for their conservation, gave themselves to inquire into the natures and properties of animals. That great Alexander, who seems to have been born for nothing more than arms, in the midst of this business, which suffices to occupy the whole man, desired so much to know the properties and natures of animals that he commanded all the hunters, and fishers, and huntsmen, and shepherds of cattle, and breeders of birds or animals that there were in all Greece and Asia, that they should obey Aristotle, and give him notice of all that each one in his faculty knew, so that he might write those so praised books of the animals. And all this was done for a little taste that the curiosity of human wit receives with the knowledge of similar things. This was certainly a small reward for so great a
labor. But how much greater is that which is promised to the religious man in this consideration, since by it he rises above the stars and above all created things, and climbs to the knowledge of that sovereign Maker, in which knowledge there is a great part of our blessedness? And thus he says by Jeremiah: “Let not the wise man glory in his wisdom, nor the strong man in his valor, nor the rich man in his riches, but in this let him glory who wishes to glory, which is to have knowledge of me.” Therefore to this so great knowledge this treatise is ordered, in which, if it should be longer than is fitting for a philosopher (for this is proper matter for philosophers), let no blame be laid upon me, since I do not treat it here as a philosopher, but as one who treats of the work of Creation, which is proper to theology, especially since all of it is referred to the knowledge of the Creator. I did it also because this matter is sweeter and more pleasant to the reader, who many times will not be able to cease marveling at the wisdom and providence of God, which in these things singularly shines forth, where he will see things in appearance so incredible that it will be necessary for him to have recourse to that memorable sentence of Pliny, who says to this purpose that the majesty of the works of nature is so great that many times it surpasses human faith and credulity. But whoever considers that in all animals God supplies the lack that they have of reason, with his providence, working in them by means of the natural inclinations and instincts that he gave them, what they would work if they had it perfect, what is said in this matter will not be incredible to him. For he who by his will and goodness alone created them, and wished them to remain in the being that he gave them, it was clear, since his works are so perfect, that he had to give them all that was necessary for their conservation, he working in them what was fitting to them for this. And thus Saint Thomas says that all these animals are instruments of God, who, as first and principal cause, moves them to all that is fitting to them by means of those natural inclinations and instincts that he gave them when he created them. But because above we said that God does not stop at this provision alone of the animals, but passes further on to manifest by this means his glory (which is discovered so much the more perfectly, as he does more and greater marvels in this), for this reason no one should hold as incredible the things that concerning this shall be said, since both the efficient cause (which is God) and the final cause (which is the manifestation of his glory) make all these works so much the more credible, as they are more admirable, and give us greater testimony of the glory of the Creator.
That memorable sentence of Aristotle also serves for this credulity, who says that the works of animals have great likeness to those of men, because what these do for their conservation, those also do for theirs. Which, setting aside other infinite examples, he proves with the art with which the swallow builds its nest. For as the mason, when he wishes to coat a wall with mud, mixes straw with the mud to bind the one with the other, so also does she in the fabric of her nest. And thus all the rest of it she makes so proportioned to the rearing of her little young, as any man of reason would do it. And according to the sentence of this great philosopher, the more the works of animals are like those of men, so much are they on this side more credible, although to those who do not consider this, they may seem more incredible. To men the Creator gave understanding and reason so that they might provide themselves with all that is necessary for their conservation, although for this infinite things may be necessary, because reason alone suffices to discover them and invent them. But with all this God is not bound to conserve the life of animals by this means, because without it he can impress in them
such natural inclinations and instincts that with these they do all that they would do if they had reason, not only as perfectly as men, but much more perfectly. For they are more certain, and more infallible, and more regular, and more constant in the works that belong to their conservation, than men in theirs. And they even pass further ahead than they, both in the knowledge of their medicines, and in guessing the changes of the airs and of the times, which men do not know except by learning them from them. All which will be seen in the process of what we shall say. Therefore in this the Creator manifested the greatness of his power and of his wisdom and providence, because, although the species of animals that there are in the sea, and on the earth, and in the air are innumerable, and seem more than the stars of heaven, in none of them, however small it may be, did he neglect even a single point, because in all of them he placed so many and so diverse abilities and faculties for their conservation, as they are, which are almost infinite. Therefore who will not remain astonished considering the greatness of that power and of that wisdom and providence, which worked so many and so great marvels in so many differences of creatures, and what is more, with a single word?
And in order to proceed in this matter orderly, first we shall treat of the properties of animals in common, and afterward we shall descend to treat of them in particular.