It is now incumbent on me to prove that all things are subjected to nature, and most beautifully directed by her.

But, first of all, it is proper to explain precisely what that nature is, in order to come to the more easy understanding of what I would demonstrate.

Some think that nature is a certain irrational power exciting in bodies the necessary motions.

Others, that it is an intelligent power, acting by order and method, designing some end in every cause, and always aiming at that end, whose works express such skill as no art, no hand, can imitate; for, they say, such is the virtue of its seed, that, however small it is, if it falls into a place proper for its reception, and meets with matter conducive to its nourishment and increase, it forms and produces everything in its respective kind; either vegetables, which receive their nourishment from their roots; or animals, endowed with motion, sense, appetite, and abilities to beget their likeness.
Some apply the word nature to everything; as Epicurus does, who acknowledges no cause, but atoms, a vacuum, and their accidents.

But when we[155] say that nature forms and governs the world, we do not apply it to a clod of earth, or piece of stone, or anything of that sort, whose parts have not the necessary cohesion,[156] but to a tree, in which there is not the appearance of chance, but of order and a resemblance of art.
XXXIII.