Like the twelve months of a calendar year, there is also a celestial or zodiacal year with twelve parts: each part is an Age or Era of 1,240 years influenced by a constellation of the zodiac.
"Each year the sun passes entirely around the zodiac and returns to the point from which it started--the vernal equinox--and each year it falls just a little short of making the complete circle of the heavens in the allotted period of time. As a result, it crosses the equator just a little behind the spot in the zodiacal sign where it crossed the previous year. Each sign of the zodiac consists of thirty degrees, and as the sun loses about one degree every seventy two years, it regresses through one entire constellation (or sign) in approximately 2,160 years, and through the entire zodiac in about 25,920 years. (Authorities disagree concerning these figures.) This retrograde motion is called the precession of the equinoxes. This means that in the course of about 25,920 years, which constitute one Great Solar or Platonic Year, each one of the twelve constellations occupies a position at the vernal equinox for nearly 2,160 years, then gives place to the previous sign... The period of 2,160 years required for the regression of the sun through one of the zodiacal constellations is often termed an age. According to this system, the age secured its name from the sign through which the sun passes year after year as it crosses the equator at the vernal equinox. From this arrangement are derived the terms The Taurian Age, The Aryan Age, The Piscean Age, and The Aquarian Age. During these periods, or ages, religious worship takes the form of the appropriate celestial sign--that which the sun is said to assume as a personality in the same manner that a spirit assumes a body. These twelve signs are the jewels of his breastplate and his light shines forth from them, one after the other. From a consideration of this system, it is readily understood why certain religious symbols were adopted during different ages of the earth's history; for during the 2,160 years the sun was in the constellation of Taurus, it is said that the Solar Deity assumed the body of Apis, and the Bull became sacred to Osiris... During the Age of Pisces, the Fish was the symbol of divinity and the Sun God fed the multitude with two small fishes... Aquarius is called the Sign of the Water Bearer, or the man with a jug of water on his shoulder mentioned in the New Testament. This is sometimes shown as an angelic figure, supposedly androgynous, either pouring water from an urn or carrying the vessel upon its shoulder... Thus the sun in its path controls whatever form of worship man offers to the Supreme Deity." —Manly P. Hall, The Secret Teachings of All Ages