Introduction to Astronomy

understands. It is not naturally through the origin of some woman, but through the motion of a certain hidden property. For there are those who think that nothing is produced except by the resolution of its own nature's female element; against these is the bipartite law of procreation. For when every body consists of a composition of the four elements, one thing takes its origin from the seed of its own genus in its nature, as a man from a man in a man; a tree from a grafted twig; an ear of corn from a received grain. Another thing comes from its own seed or genus, but they meet in matter and bring forth grasses and shrubs of that same genus. Gems also and other metals, which freeze from diverse vapors. Some animals also are produced neither from air nor from aquatic and terrestrial things—as are flies, frogs, fleas, and things of that kind—all of which follow certain motions of the elements through the vicissitudes of time, not produced from any seed of their own genus in their nature.

Chapter Four. On the confirmation of astrology.

An ornamental woodcut initial 'H' featuring scrolling foliage within a square frame.

With these things arranged in this way, now reason must be given in astrology, and at the same time one must respond to those who contradict it. For there are those who deny power and efficacy to sidereal motions, disagreeing in ten sects. The first of these holds that the stars have no guidance toward any effects or corruptions of things in the sublunary world, to which all ancient authority answers. For if the impulse of the twin-natured celestial bodies agitates natural motion in another thing, it is necessary that, being bound to it by related chains, it causes a natural resolution. Since this is so, it follows that the cause of its resolution is the very effect of its cause; for in this way, the natural motion of fire in related matter causes a natural resolution, I mean combustion. Therefore, fire is the cause of combustion, and combustion is the effect of this cause. In this way, therefore, when celestial bodies surround the lower world, they naturally animate their motion in the elements of this world naturally annexed to them, resulting in the resolution of one into another, which follows every generation and corruption of nature. Since, therefore, celestial motion is the cause of elemental resolution, it is necessary that this resolution of effects and corruptions, and those same effects and destructions, follow the celestial motion. For the corruption of one thing is the generation of another; the combustion of wood is the effect of charcoal, and the corruption of charcoal generates ash. Hence, the saying among the wise: the natural and perpetual motion of the stars is the perpetual effect of nature. The opinion of the second sect is that the stars have guidance toward general and universal things, such as the genera and species of things, the alterations of times, and the resolutions of elements and that kind, but not toward individual things, or their parts, or their individual properties. Against these, it has been discussed in all philosophy: since every body of this world consists of a composition of the four elements. Indeed, in every body, the motions of the stars are felt, for they are present with them and have power over them. For since celestial motions are the cause of elemental resolution, and resolution is the cause of generations, it follows that generations are also the effect of those motions. Also,