Midpoint Tree

MID-poynt tree

Definition

A midpoint tree is a computed list that takes every planet and chart point in a horoscope and checks it against the midpoints — the halfway degrees — of every pair of other points, sorted by zodiac position. For each point, the tree shows which planet-pair midpoints land within a chosen orb of that point's degree, written A/B = C, where C is the point. In Cosmobiology and Uranian practice it is usually read on a 90° or 45° dial.

In Tradition

In Cosmobiology and Uranian astrology, the midpoint tree is the main analytical tool for spotting clusters of planetary pairs that ordinary aspect analysis would not reveal. A planet that sits on several pair-midpoints is read as carrying an intensified theme — the more midpoints it occupies, the more it acts as a focal point in the chart. The tree swaps aspect-only reading for a denser symbolic picture of how the planets integrate.

In Practice

Astrologers build the midpoint tree by working out every two-planet midpoint in the chart — and often midpoints that involve the angles, the nodes, and the Arabic Parts — then sorting those midpoint positions by zodiac longitude. Each chart point is then tagged with which midpoint pairs fall within an orb, commonly 1°30′ or tighter for 45° dial work, sometimes 2° for the 90° dial. The astrologer reads the tree by treating the planets with the densest midpoint clusters as the chart's structural focal points, and interpreting each cluster's combined meaning through Ebertin's pair-by-pair reference dictionary. The 90° dial lays out all points and midpoint pairs at quarter-circle scale, so that the hard-aspect contacts — 0°, 45°, 90°, 135°, 180° — all collapse onto a single bodily conjunction, which makes them easy to spot.

Historical Origin

The midpoint-tree technique was developed in 20th-century Germany by Reinhold Ebertin within the Cosmobiology school, and set out in *The Combination of Stellar Influences* (Kombination der Gestirneinflüsse, from 1940 onward). The 90° dial it relies on comes from the related Uranian tradition that Alfred Witte founded in Hamburg in the 1920s. The technique has no Hellenistic, Arabic, or pre-modern Western precursor.

Definition

In Tradition

In Practice

Historical Origin

Further Reading