The majority of people know very little concerning the purpose of the characters of the Zodiac. Its an amazing phenomenon that twelve of the most common symbols in the world, those of the twelve Zodiac signs, are largely a mystery to why each of these beings (whether human or animal) were chosen to represent these specific constellations. This small treatise was taken from The Compost of Ptolomeus which can be found in the Library section of this website.
Each one of the twelve Signs was designated an animal, human or inanimate object through by its influence on the Earth when the Sun passes through each of them. In each duration of the Suns crossing of these signs throughout the year the conditions on earth change. Each of these changes is assimilated to the virtue of a specific idea that is represented by that animal, human or inanimate object.
Wherefore the first is called Aries, that is to say, the Ram because the Sun going by that part, approacheth near the course of the places and his heat, mixed with the moistness, beginneth to augment little and little and the Air doth temperate itself, which is a thing nigh unto the nature and complexion of the Ram.
The second is called Taurus, that is to say, the Bull because the Sun being upon him, his heat doth augment, and the moistness resolved, maketh a temperateness of the Air drawing to dryness, a thing much agreeing to the nature of a Bull.
The third is called Gemini, that is to say, twins, or two children joined in one, because that in this season doth augment double, and the males of all kinds of beasts do join and couple with the females, for the increase and bringing forth of their shape.
The fourth taketh his name of the Crab and is called Cancer, which is a beast that goeth backward, by the reason that the Sun returneth toward the Equator, whence he first came, in observing the descent and declinations of a contrary order unto that which he had in Gemini.
The fifth because of the extreme heat is then accompanied with dryness, taketh the name of a Lion, for the Lion is strongest of all the beasts, and of the complexion hot and dry.
The sixth is attributed unto the Virgin, which is a thing barren and very weak, for then the heat diminisheth; and the dryness which he bringeth in, hath dominion, by means whereof all things do cease to grow and to increase and become barren, except (it may be) the extreme concoction of some.
The seventh after is not only called Libra, or the Balance because that the days and nights be then equal but also because it maketh alike weight and measure of the qualities between the heat which then faitheth, and the cold which doth then begin to come in.
The eighth is called the Scorpion, as the part venomous and mortiferous of the year, for by the dryness which then doth excel and in his force and the coldness brought in, which be two qualities enemies unto nature there cometh corruptions of the Air and by the means pestilences or other dangerous diseases.
The ninth is called the Archer and is called Sagittarius, for when the Sun cometh upon this Sign, his heat being vanquished, the cold hath dominion, and thereof cometh fogs, snows, frosts, and other such pernicious alterations, hurting on all parts of the beasts, and all things having the vegetive life, as if they were darts or arrows venomed.
The tenth beareth the name of the Buck, and is called Capricornus, which is a beast of cold nature, dry, and melancholy : for the Sun being then gone farthest away of all the year, he goeth from our climate and region and by that cause the Air becometh distempered, by the occasion of the great and extreme cold that is then accompanied with dryness.
The eleventh is called Aquarius, that is to say, a caster of Water because that dryness failing, moistness cometh in again, for then the Sun returneth towards the Equator and by reason of coldness, which then is Lady, there cometh much snow and rain.
Finally, the twelfth and last Sign hath not without great occasion taken the name of Fishes, because they be beasts of the water, for then the coldness of the time beginneth by little and little to end : and by the coming of the Sun into the tops of our regions, the moistness frozen and congealed doth dissolve, and thereof cometh a temperateness of the Air, much watery and rainy.
With this said, it is very clear that each sign of the Zodiac is a symbol of the changing effects the Sun's revolution had on the Earth and therefore these objects (whether animal, human or inanimate object) were associated with each of the constellations.