By the fifth century BC, the Zodiac, which represents the 12 Zodiac Constellations, was used by the Astrologers in Mesopotamia.

The Astrologers that followed, known as the Hellenistic Astrologers, assigned significations, that is meanings, to each of the 12 Zodiac Signs. Caveat! The Significations varied from Astrologer to Astrologer.

According to Chris Brennan, the renown Denver Astrologer, the Significations of the Zodiac Signs are primarily contingent on (1) the Signs' Modality (for example, Cardinal), (2) the Signs' Element (for example, Fire), (3) the Signs' Gender (for example, example, Masculine), and , (4) the Signs' Ruling Planet (for example, Aries is ruled by Mars).