Introduction to Astronomy

...changed characters, and things of that kind. Every individual, therefore, consists of three principles: the properties of form, the properties of matter, and the effect of the stars original: "sidereqz effectu". Those things, therefore, which come about according to that effect, follow different bodily leaderships: some are specific and others are general. For example, the Sun is the singular leader of life and the general leader of all living beings; Mercury is the leader of man. Thus, while the stars proceed in the singular leadership of things, they nevertheless take on a participation in the common duties of others. For instance, while the Sun singularly leads the general substance of one man, Mercury takes on a shared role in perfecting specific common traits. Therefore, in one man, there will be the Sun’s specific leadership of the animal substance, but a shared leadership over the heart and the brain. Mercury holds singular leadership over the human substance, with participation in the mouth and the tongue. With others taken into participation: Saturn governs the spleen; Jupiter the liver; Mars the blood; and so others proceed to other parts. Thus, in all bodies, they claim their parts and all properties and accidents through a dual leadership. If these did not consist of diverse leadership, it would not be possible for them to stand out from diverse parts, qualities, properties, or accidents. Now, however, in the leadership of things, there is a hierarchy of stars: some govern the genus, some the species, some the individual, and to others, at different times, different qualities, quantities, and other accidents proceed. Hence it is that we see the contemplation of even individuals and their natural properties proceed differently from one another; because this is understood not as a material or formal power, but as a sidereal virtue The "virtue" or power of the stars. This is not by the natural origin of some seed within itself, but by the movement of a certain secret property. For there are those who think that nothing is procreated except from the breaking down of the seed of its own nature; against these, there is a two-part law of procreation. For while every body stands composed of the four elements, one is nevertheless procreated in its own nature from the origin of its own kind of seed—as a man from a man in a man, a tree grafted from a small branch, or a grain of corn from a received seed. But another kind is produced not from any seed of its own genus, but from materials coming together, which give birth to grasses, shrubs, and that kind of thing. Likewise, gems and other metals are congealed from various vapors. Also, some animals are produced from the air, as well as from aquatic and earthy sources—such as flies, frogs, fleas, and that kind of thing—all of which follow certain movements of the elements and changes of the seasons, procreated in their nature not from any seed of their own kind.

Chapter 4: On the Confirmation of Astrology

Decorative woodcut initial 'H' featuring a scholar or astronomer seated at a desk within an architectural frame.
With these things arranged in this manner, it now seems that a rational account must be given for astrology, and at the same time, a response must be made to those who contradict it. For there are those who deny force and efficacy to the sidereal ways, disagreeing in ten sects. The first opinion, indeed, is that there is no leadership at all in the stars toward any effects or the corruption of things in the sublunary world The world below the moon, i.e., Earth; to which all ancient authority responds. For since every substance is agitated by a dual impulse, it must necessarily cause a natural resolution A breaking down or change in another thing bound to it by related ties. Since this is so, when the cause of that resolution is the motion itself, and the effect of that cause is present: in this way, the natural motion of fire, received in matter of a related nature, causes a natural resolution—I mean burning. Fire is therefore the cause of the burning, and the burning is the effect of this cause. In this same manner, the celestial bodies...