The Triangle

http://wisdomportal.com/Geometry/GeometryPage.html

The triangle represents the sacred Trinity. The apex pointing upward stands for the ascent to heaven, fire, and the active male principle. When the apex is pointed downwards, it symbolizes grace pouring from heaven, water, and the passive female principle (Taoist spirit of the valley). Two equilateral triangles, one with apex up and the other down, represents fire & water— superimposed so as to form a 6-pointed star (Solomon's seal or the Judaic Star of David), and is used as a symbol of the human soul.