The century the zodiac arrived, the gist

The century the zodiac arrived

The twelve zodiac signs, the twelve houses, the idea of aspects and the seven-day week all came into India from the Greek world in the first few centuries of the common era, and were fitted onto a much older Indian way of dividing the sky.

This is the short way in. The essay has the working, the sources and the sky.

The Sanskrit names for the zodiac signs were once just Greek names written in Indian letters. A sixth-century textbook still lists them: kriya for Krios the ram, leya for Leon the lion.

An Indian birth chart, a diagram of where the sun, moon and planets stood at the moment somebody was born, divides the same circle twice over.

The first division is into twenty-seven parts called nakshatras, or stations, each a fixed slice of sky named after a star or small star group. The almanac uses them daily to say where the Moon is.

The second division is into twelve parts of thirty degrees each. These are the signs: ram, bull, twins, and so on, what people mean by your sign.

The two are not the same age in India: the stations are old here, the signs came from outside.

The oldest surviving Indian book about the sky has no signs in it. No houses, no aspects, nothing about anybody's life. It is a calendar manual for working out the date of a ritual.

The signs came from the Greek-speaking world, with three other things. The houses, twelve divisions counted from the point rising in the east at birth. Aspects, the idea that two planets at a set angle from each other should be read together. And the seven-day week, which the old Indian calendar did not have.

The biggest import was a question. The old manual asked when a ritual should be held, never what a person is like. Reading a birth for a life is the borrowed idea, and the rest is equipment for doing it.

You can see the borrowing in the words themselves. Kendra, the term for the angular houses, is the Greek kentron. Even hora, the word in the title of the tradition's largest handbook, is the Greek word for an hour.

Nobody can give a year for it. Greeks and Indians were in contact for four or five centuries before any of this shows up in a datable book, and contact is not transmission. The two dates people usually quote, 149 and 269 of the common era, came from one scholar's repairs to a damaged manuscript line, and they no longer hold. By the year 500 the system was in place and completely at home.

Words decoded

jyotisha (ज्योतिष): the Indian tradition of sky-reading, covering both astronomy and astrology
birth chart: a diagram of where the sun, moon and planets stood in the sky at the moment and place somebody was born
nakshatra (नक्षत्र): one of twenty-seven fixed slices of the sky, named after stars; the older Indian way of dividing the circle
rashi (राशि): one of twelve slices of thirty degrees each; a zodiac sign
graha (ग्रह): one of the moving bodies a chart tracks, the sun, the moon, five planets and two calculated points
ascendant: the point of the sky rising in the east at the moment being examined; the chart is built outward from it
house: one of twelve divisions counted from the ascendant
aspect: a fixed angle between two grahas that the tradition reads as a link between them
yavana (यवन): originally an Ionian, that is a Greek; later a Sanskrit word for a westerner of any kind
Varahamihira: the sixth-century author whose books are the earliest securely dated place where all of this material sits together

Why anyone should careTwo opposite stories get told about Indian astrology, that it is unchanged since the beginning of time and that it was copied wholesale from the Greeks. Both are wrong, and the true story is more interesting than either. Knowing when a piece of a system arrived lets you weigh it, instead of accepting or rejecting the whole inheritance in one go.

Read it properly, 8 min The century the zodiac arrived