Part of Basis

The Lot of Basis, kleros baseos, also called the Lot of Foundation, is calculated from Fortune and Spirit together, taking the shorter arc between them and projecting it from the Ascendant, so that it stands as the single point in which the two principal lots are combined. It is read as the underlying support of the life, the base on which the whole rests, and in some Hellenistic material it is used in judgments about the length of life and the fundamental condition of the native. Because it depends on both of the primary lots it inherits their sect reversal twice over, and it is one of the points most likely to be calculated differently by different software; anyone comparing results should check the formula in use rather than assume agreement.

Because Basis draws on both principal lots, and each of Fortune and Spirit already reverses its own terms between a day and a night birth, the lot is sometimes described as carrying a double sect sensitivity, though in practice the shorter-arc construction from Fortune to Spirit, or Spirit to Fortune, projected from the Ascendant, is computed the same way regardless of sect once Fortune and Spirit themselves have been correctly placed for the birth in question; the sect reversal is fully absorbed into the two lots that feed it rather than applied a second time to Basis itself. This is a point of frequent confusion in modern software implementations, some of which apply an unwarranted additional reversal to Basis and so arrive at a different degree than the classical construction gives.

The day formula stored for this lot is Ascendant plus the Lot of Fortune minus the Lot of Spirit. Both underlying lots contain the Ascendant, and by day Fortune is Ascendant plus Moon minus Sun while Spirit is Ascendant plus Sun minus Moon. Substituting both and cancelling gives Ascendant plus twice the Moon minus twice the Sun.

So Basis keeps exactly one Ascendant, which is what one might expect, but it carries the Moon and the Sun at double weight. That is the arithmetic behind the doctrinal description of it as the point where Fortune and Spirit are combined: the two Ascendants of the underlying lots cancel to one, and the lunar and solar terms reinforce rather than cancel.

Its motion is the Ascendant's plus a little. Twice the Moon is about 26 degrees 22 minutes a day and twice the Sun about one degree 58 minutes, which together add roughly 24 degrees to the Ascendant's full circle. The lot advances one degree every three minutes and forty five seconds, slightly faster than the Ascendant itself, so it needs a birth time recorded to the minute in the same way the Ascendant does.

There is one further property worth noting. Because the Moon and Sun enter at double weight, the distance between Fortune and Spirit in a chart, which is twice the elongation of the Moon from the Sun, is also the distance from the Ascendant to Basis. The lot sits at a lunar phase angle measured out from the horizon.