Applying & Separating

The distinction between applying and separating aspects is one of the most practically important refinements in traditional astrology. William Lilly (Christian Astrology, 1647, p. 111) defined the terms precisely: a planet is applying to another when the faster-moving planet is moving toward the degree of exact aspect, and separating when it has already passed exactitude and is moving away. An applying aspect represents something coming into being — the influence is building and the matter is still unresolved. A separating aspect represents something already past — the influence is waning, the matter is largely concluded. In horary astrology, Lilly relied heavily on this distinction for timing: an applying trine between significators indicated the matter would come to a positive conclusion; a separating trine suggested the opportunity had just passed. The same principle extends to transits and natal interpretation. Applying transits (when a transiting planet moves toward exact contact with a natal point) are the active, forward-moving phase of a transit's influence. Separating transits represent the unwinding and integration phase. In natal charts, applying aspects are often considered to have stronger character-building force because the energy is perpetually moving toward resolution rather than away from it. Planets that are mutually applying — each moving toward the other — carry the most force.