The Arithmetic of Children: Two Slow Planets and an Angle

The day formula stored for this lot is Ascendant plus Saturn minus Jupiter. Both planetary terms are slow: Saturn moves about two minutes of arc a day and Jupiter about five, and they are subtracted one from the other, so between them they change the lot by roughly three minutes of arc a day in the ordinary case.

The motion of the lot is therefore the Ascendant's and nothing else worth counting. It advances one degree every four minutes and covers the whole zodiac in a day.

That gives an unusually clean statement of what the lot depends on. Everything individual about a Lot of Children is the birth time. Two people born on the same day anywhere in the world have their Saturn and Jupiter terms in common to within three minutes of arc, so the entire difference between their lots is the difference in what was rising. A birth time wrong by two hours puts the lot in the wrong sign; a birth time wrong by four minutes puts it in the wrong degree.

There is a second point in the relationship between the two planets. Saturn minus Jupiter is the elongation between the two slowest classical planets, which returns to the same value about every twenty years at each Jupiter and Saturn conjunction. The lot therefore carries a twenty-year cycle inside it that is shared by everyone born in the same period, and only the Ascendant distinguishes them.