Diagram of planetary courses in the zodiacal signs — "In this diagram, the names of the seven planetary bodies – the Sun, the Moon, and the five known planets – are written along the vertical, at left. At top, along the horizontal, are the zodiacal names. One may follow the path of each planetary body through the zodiac by reading the graph from left to right. The diagram gives a sense not only of the independence of each planet’s orbit, but also of the different lengths of time it took each planet to complete one circuit of the zodiac. Along the bottom of the diagram is a list of the planetary bodies, with their distances given as musical values -- a tone (tonus), a semitone (semitonium), or three semitones (tria semitonia) -- as well as an abbreviated account of interplanetary distances, given as proportions of the distance from Earth to the Moon."