Great Year
From The Art and Popular Culture Encyclopedia
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The term Great Year has a variety of related meanings. It is defined by NASA as "The period of one complete cycle of the equinoxes around the ecliptic, about 25,800 years […] also known as [a] Platonic Year." One complete cycle of the equinoxes here means one complete cycle of axial precession, this precession was known to Plato, who defined the "perfect year" as the return of the celestial bodies (planets) and the diurnal rotation of the fixed stars (circle of the Same) to their original positions, from his studying in Egypt for 13 years. Cicero followed Plato in defining the Great Year as a combination of solar, lunar and planetary cycles (61 XX) Nicholas Campion writes of "periods of History, analogous to the solar year, known as 'Great Years' "
Plato's description of the perfect year is found in his dialogue Timaeus
- And so people are all but ignorant of the fact that time really is the wanderings of these bodies, bewilderingly numerous as they are and astonishingly variegated. It is none the less possible, however, to discern that the perfect number of time brings to completion the perfect year at that moment when the relative speeds of all eight periods have been completed together and, measured by the circle of the Same that moves uniformly, have achieved their consummation."
In De Natura Deorum, Cicero wrote
- On the diverse motions of the planets the mathematicians have based what they call the Great Year," which is completed when the sun, moon and five planets having all finished their courses have returned to the same positions relative to one another. The length of this period is hotly debated, but it must necessarily be a fixed and definite time."
By extension, the term "Great Year" can also be used for any concept of eternal return in the world's mythologies or philosophies. Otto Neugebauer wrote
- "The difficulty with the term "great year" lies in its ambiguity. Almost any period can be found sometime or somewhere honored with this name."
See also
