TREATISE I. BOOK III.

Furthermore, here we have more precisely constructed the world monochord with its proportions, harmonies, and intervals, and we have depicted its mover as being outside the world in this manner.

A detailed 17th-century engraving shows the World Monochord original: "monochordum mundanum". This image illustrates the music of the world original: "musica mundana", the theory that the universe follows musical laws. A single-stringed instrument covers the entire cosmos. At the top right, a divine hand reaches out from a cloud to turn a tuning peg. This shows God as the prime mover original: "motorem" existing outside the physical world. The bottom of the instrument is fixed in the Earth original: "Terra".

The neck of the instrument shows the layers of the universe. At the bottom is the Elemental Realm: Earth, Water, Air, and Fire. Above this are the planetary spheres. These are marked with symbols for the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. The top sections represent divine realms: the Region of Appearance original: "Epiphionia locus", the Region of Spiritual Law original: "Epiphionomia regio", and the Seat of the Epiphany original: "Epiphania Sedis pars".

Arcs on the sides show mathematical and musical relationships. On the right are musical intervals: the Material Fourth original: "Diatessaron materialis", Material Fifth original: "Diapente materialis", and Material Octave original: "Diapason materialis". Higher up are the Formal Fifth, Formal Octave, and Formal Fourth. The entire string represents a Double Octave original: "Disdiapason". On the left are ratios like the Double Proportion, Triple Proportion, and Quadruple Proportion.

The musical scale is written along the string using letters. It marks whole tones and semitones. A band of stars representing the zodiac crosses the string at the level of the Sun.