The triangle of art represents the protected space outside the magic circle, into which spirits are compelled to appear in Solomonic ritual magic. Typically, the central circle is inscribed with the sigil (seal) of the spirit to be invoked. The usual form is of a triangle, circumscribed with various words of power, containing an inner, blackened circle. The purpose of the triangle is to contain the manifested entity. In some cases, the triangle is created as a physical object; sometimes, the central circle is replaced with a black scrying mirror.
Triangles from various grimoires