The Sphere of the World

...which means "life," because according to the motion of the planets beneath it, all life in lower things Referring to the terrestrial world below the moon's sphere is governed. Or it is named from zodion original: "zodion", which means "animal." This is because, since it is divided into twelve equal parts, each part is called a sign, and each has a special name taken from the name of an animal. This is either because of some shared property between the sign and the animal, or because of the arrangement of the fixed stars stars that appear to stay in a permanent position relative to each other in those parts, which resemble such animals.

This circle is called the Sign-bearer original: "signifer" in Latin, because it carries the signs or is divided into them. By Aristotle The Greek philosopher (384–322 BC) whose physical theories dominated medieval science in his book On Generation and Corruption, it is called the oblique circle. He says there that according to the approach and retreat of the sun along this oblique circle, the generation and decay of all lower things occur.

The names of the signs, their order, and their number are shown in these verses:
Aries, Taurus, Gemini, Cancer, Leo, Virgo;
Libra, Scorpio, Sagittarius original: "architenes," literally "the bow-holder", Capricorn original: "caper", Aquarius original: "amphora", and Pisces.

Each sign is divided into thirty degrees original: "gradus". From this, it is clear that in the whole zodiac there are 360 degrees. Furthermore, according to astronomers, each degree is divided into sixty minutes; each minute into sixty seconds; each second into sixty thirds, and so on down to tenths. Just as the zodiac is divided by the astronomer, so too is every circle in the sphere—whether large or small—divided into similar parts.

However, while every other circle in the sphere except the zodiac is understood as a simple line (like a circumference), the zodiac alone is understood as a surface having a width of twelve degrees, of the sort we have just discussed. From this, it is evident that some speak falsely in astrology when they say the signs are square, unless they are misusing the term and calling a rectangle a "square." For a sign has thirty degrees in length, but twelve in width.

The line that divides the zodiac around its circumference, so that it leaves six degrees on one side and six on the other, is called the ecliptic line. It is so named because when the sun and moon are aligned directly beneath it, an eclipse of the sun or moon occurs. A solar eclipse happens if there is a new moon original: "novilunium" and the moon is placed directly between our view and the solar body. A lunar eclipse happens at the full moon original: "plenilunium" when the sun is diametrically opposed to the moon. Thus, an eclipse of the moon is nothing other than the Earth coming between the bodies of the sun and the moon.