The Measure of the Circle | Math for Mystics

Pi (π) is the ratio of the circumference of a circle to its diameter. 
As a fraction, its closest approximations are 22/7, 333/106 and 355/113.

Projection on the plane of the ecliptic of the parabolic
orbits of 72 comets, 1802. Engraving by Wilson Lowry after
Johann Elert Bode.

Circle of Fifths, and relationship of relative
minor keys to major key signatures.

 

"The circle is one of the noblest representations of Deity, in his noble works of human nature. It bounds, determines, governs, and dictates space, bounds latitude and longitude, refers to the Sun, Moon, and all the planets, in direction, brings to the mind thoughts of eternity, and concentrates the mind to imagine for itself the distance and space it comprehends. It rectifies all boundaries; it is the key to information of the knowledge of God; it points to each and every part of God's noble work."

John Davis (1845): The Measure of the Circle [p. 12].