Just as the magnet attracts iron, and other matter is often seen to be drawn along by its adherence to the iron, so too is this mode of acting—one thing upon another through a certain property of nature—found in many things, both in herbs and in stones, just as fire knows colophony a type of pine resin and oil (that is, the fat of the olive). In this same way, therefore, the celestial essence is seen to act entirely upon the nature of the lower world. For since a power of this kind exists in that [celestial] nature, and the nature of this [lower world] is receptive to such power, a mingling of generations occurs from this action and passion In medieval philosophy, "passion" refers to the state of being acted upon by an external force, which is the mother of all things. Since, therefore, the stars are the cause of the generation of things, it follows that they hold the leadership of that same generation.

There are, however, some who think that whatever exists from another thing for the sake of something else is the same, and they assert that nothing can be done by another across a distant interval; among these people, there are three diversities of such motions. First, that which acts; second, that which is made by the actor; third, that which follows from something as a consequence. To act, moreover, happens in two ways: by will and by nature. By will, such as walking, standing, or sitting. By nature, such as fire burning. To be made happens similarly by will and also by necessity: by will, such as writing a letter; by necessity, such as matter being consumed by fire. But that which happens for the sake of something else is different from these. For it is not made by another acting, but follows from another preceding it, just as shame is followed by a blush, or fear by paleness.

Musical melodies are consonant with the motions of the soul and body; in this manner, therefore, when the celestial bodies are carried by their natural motion above this world, the natural motions of the elements of the lower world follow, being bound to them, producing the generations and corruptions of things. For example: when the Sun traverses a quadrant of the first circle, we see the elements tempered by hot and moist qualities. And so we see the earth and trees clothed with herbs and leaves, adorned with flowers; and thus the corruptions of some things and the generations of others occur in this way—not from any deliberation of the Sun, but by a divinely enjoined duty of traveling through the circle, to which the nature of things is adapted by such motions.

Finally, we subjoin the discourse of the philosophers: since the circle moves, it must have a moving cause, which, unless we understand it, we shall be led into infinity. But the motion of the circle is infinite, wherefore the moving power must be both infinite and incorporeal. Thus, it follows that the cause of all alteration and corruption is external.

On the Quality of Effects. Chapter 3.

A large historiated woodcut initial 'Q' containing a portrait of a philosopher or scholar wearing a flat cap and academic robes. The figure is shown in profile within a circular frame, which is set inside a square decorative border with floral or foliate motifs in the corners.

There are four kinds outside of which no species of things in the lower world exists; by explaining these, it may easily be revealed what powers of the stars have chosen regarding the accidents of this world. These are: Form, Matter, Composition, and the Composite.

We shall use, therefore, the mode of speaking common among the philosophers, by which they call "human form" that by which every individual of this species is called "human," and "equine form" that by which a horse is so called. Matter, however, or the fourfold nature, consists of: earth, water, air, and fire. Composition is the harmony of the elements within bodies. The Composite, moreover, is that which results from such a composition, such as all bodies of living creatures, seeds, and metals. In all these bodies that we perceive, these four kinds are found: first, that which is composed; second, the composition; third, the nature; fourth, the species. These being so arranged, we subjoin the discourse of the philosophers: that the mother of every generated thing is more ancient than the thing itself, and leads the generated thing toward the perception of being.