The Lot of Spirit, kleros daimonos in Greek, is the counterpart of the Lot of Fortune and the second of the two on which the whole Hellenistic system of lots is built. A lot is a point derived by arc: the distance between two significators is measured and projected from the Ascendant, so that the lot carries the relationship between them to a place in the chart. Spirit is measured from the Sun as Fortune is from the Moon, and the two are reflections of one another across the Ascendant. Vettius Valens treats the pair at length in his Anthology, and the division of meaning is consistent: Fortune concerns the body, health, livelihood and what happens to a person, while Spirit concerns the mind, the will, deliberate action and what a person does. The pairing is one of the most characteristic features of Hellenistic technique and was largely lost in later western practice.
The formula makes the sect reversal explicit: by day, Spirit is found by measuring the arc from the Moon to the Sun and projecting that same arc forward from the Ascendant, Ascendant plus Sun minus Moon; by night the terms swap, Ascendant plus Moon minus Sun. This is the exact mirror of the formula for Fortune, which runs Ascendant plus Moon minus Sun by day and reverses by night, and the mirroring is the point: Fortune and Spirit are built from the same two lights in opposite order, so that whichever light leads by day trails by night, and the pair together map the two halves of the person, body and mind, onto the two possible birth conditions. Getting the day and night terms swapped, rather than merely omitted, is the single most common technical error made with this and every other sect-reversing lot in the Hellenistic set.