Complete Works, Volume Four

The Colures The Colures are two principal meridians of the celestial sphere that pass through the celestial poles and either the equinoxes or the solstices. designate four points in the Zodiac called the Cardinal points. These are the Beginning of Aries, where the Sun is when night is equal to day and Spring begins; the Beginning of Cancer, where the Sun is when the day is longest and Summer begins; the Beginning of Libra, where the Sun is when night is again equal to day and Autumn begins; and the Beginning of Capricorn, where the Sun is when the day is shortest and Winter begins. These common verses refer to this:

Two points make the Solstice, Cancer and Capricorn;
But Aries and Libra make the nights equal to the days. original: "Hâc duo Solstitium faciunt, Cancer, Capricornus; Sed nocteis æquant Aries, & Libra diebus." These mnemonic verses were frequently used by students to remember the solar cycle.

It should also be noted that it is a property of the Solstitial Colure that the Poles of the Zodiac are designated within it. Specifically, they are at two opposite points where the Colure intersects the Polar circles, which are equally distant from the Zodiac on all sides.

CHAPTER XI.

On the Zodiac and the Ecliptic.

The Zodiac is that wide circle, laid over the other moving circles, which touches the Tropics on either side and cuts the Equator at an angle. It is marked by twelve figures and is divided lengthwise by a middle line called the Ecliptic. It separates the Sphere into Northern and Southern parts.

It represents a corresponding circle in the Heavens, one that is wide and oblique, holding the same relationship to the Equator and the Tropics. It is similarly divided by the line called the Ecliptic, distinguished by twelve Asterisms In this context, "Asterisms" refers to the constellations or groups of stars that form the zodiacal signs., and similarly divides the Heaven into two Hemispheres, one Northern and the other Southern.

It is called the Zodiac because these Asterisms are mostly painted in the forms of animals original: "ζῳδίων" (zōidion). Because these Asterisms are called Signs, the circle is also called the Sign-bearer. Due to its tilted position, it is also frequently called the Oblique circle.

Furthermore, it is determined to be "wide" because when the Planets move through it, they do not all keep to the same path. While the Sun travels through the middle along the line called the Ecliptic, the other planets pursue paths that are tilted in relation to this line. Because their paths intersect the Ecliptic in two opposite places, they deflect sometimes to the North and sometimes to the South. Some deflect more, others less. Therefore, it is appropriate to attribute a width to this circle that encompasses these deflections, which are roughly six, seven, or eight degrees on either side.

Regarding the motions of the Planets, this will be discussed more explicitly in the following section on Theory. Here, because of what remains to be said about the Sphere, something must necessarily be anticipated regarding the motion of the Sun.

Thus, although the Sun is carried away by the First Mover and completes a circuit daily from sunrise to sunset, it nevertheless returns by its own slow motion and tends toward the east. It moves obliquely along the path of the Zodiac, much like a sailor who is carried along by a ship but can walk in the opposite direction, from the bow toward the stern.

I call this motion slow because the Sun completes only about one degree by this motion within one day, or twenty-four hours. It does not complete a full circuit except within a year. Just as an ant can be carried by a wheel and spun around completely a hundred or more times, yet meanwhile move in the opposite direction to complete one full revolution of its own, so the Sun is carried by the First Mover and spun toward the west three hundred and sixty-five times, while in that time it revolves once by its own motion toward the east.

This is the motion by which the circle or Orbit of the Sun is described through the middle of the Zodiac. They call this the Ecliptic line because the Moon, crossing this line when it is joined with or opposite to the Sun, produces an Eclipse of itself or of the Sun, as will be discussed below.

CHAPTER XII.

On the Signs of the Zodiac.

It has already been stated that the Signs of the Zodiac are twelve in number. Here are the characters by which they are usually represented: Aries ♈, Taurus ♉, Gemini ♊, Cancer ♋, Leo ♌, Virgo ♍, Libra ♎, Scorpio ♏, Sagittarius ♐, Capricorn ♑, Aquarius ♒, and Pisces ♓.

The custom is to attribute 30 degrees to each Sign. Even though the physical Asterisms themselves are unequal to each other, some being shorter and others longer, there are exactly 30 degrees when 360 is divided by 12.

The starting point is taken from Aries, which is the intersection of the Vernal Equinox. The Asterism of Aries was near this point when the study of Astronomy began in Greece about two thousand years ago.

Although this Asterism has since moved away due to the slow motion of the Firmament (which will be discussed later) and has almost entirely passed into the place where the Asterism of Taurus used to be, the first 30 degrees always retain the name of Aries. Similarly, the following 30 retain the name of Taurus, even though the Asterism of Taurus now occupies the place of Gemini, and so on for the others.

Because of this, for the sake of distinction, these thirty-degree segments are not called Asterisms, but are called the Signs of Aries, Taurus, Gemini, and so on. They are also called Dodecatemoria The word comes from the Greek for "twelfth-parts." because they are the twelve parts of the Zodiac.

A Sun or another Planet is said to be "in" a certain Sign when it is beneath it, or when it is positioned between our eye and that Sign. The Fixed Stars that are outside the Zodiac are said to be in a Sign, or rather referred to that Sign, when they fall between that Sign and the nearest Pole of the Zodiac.

Of these Signs, ♈, ♉, ♊, ♋, ♌, ♍ are called Northern; ♎, ♏, ♐, ♑, ♒, ♓ are called Southern. Furthermore, ♑, ♒, ♓, ♈, ♉, ♊ are called Ascending; ♋, ♌, ♍, ♎, ♏, ♐ are called Descending.

Again, ♈, ♉, ♊ are called Vernal (Spring); ♋, ♌, ♍ are called Estival (Summer); ♎, ♏, ♐ are called Autumnal; ♑, ♒, ♓ are called Hyemal (Winter).