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Twelve shows up everywhere in religious record keeping: months, signs, titans, apostles, animals, meridians. Some of that is one number borrowed and passed along. Some of it is not related at all, and arrived at twelve by a completely different road.

A Dozen, Ten Times Over

The atlas holds at least ten separate systems that settle on twelve members: the zodiac signs, the rashis of Vedic astrology, the twelve astrological houses, the twelve animals of the Chinese zodiac, the twelve earthly branches they are paired with, the twelve months of the Islamic calendar, the twelve classical Titans of Greek myth, and the twelve original apostles, counted separately from Paul, who is recorded alongside them but was not one of the Twelve.

The Hebrew calendar keeps its own honesty about the number. An ordinary year has twelve months. A leap year adds a thirteenth, Adar II, rather than forcing the count to stay at twelve by any sleight of naming.

Not the Same Twelve Twice

What makes the count worth pausing on is that these twelves are not one twelve wearing different clothes. The zodiac signs and the months of a lunar calendar share a common root in the roughly twelve lunations of a solar year. The Chinese earthly branches share a different root, tracking Jupiter, which orbits the sun in close to twelve years.

But the twelve primary meridians of Chinese medicine map the body, not the sky, and have no lunar or planetary parent at all. Neither does the twelve-tone scale that Western music is built from. Twelve turns out to be a number several unrelated systems arrive at on their own terms, sometimes because of the sky and sometimes for reasons that have nothing to do with it.

Where To Read More

• AriesOne of the twelve zodiac signs, part of the calendar family of twelves
• ZiWater BranchesOne of the twelve earthly branches, tracking Jupiter rather than the moon
• LungOne of the twelve primary meridians, a bodily twelve with no sky behind it
• Adar IIIntercalary MonthsThe leap month that honestly makes some Hebrew years thirteen, not twelve