“The heaven of Jupiter may be compared to Geometry on account of two properties. The first is, that it moves between two heavens repugnant to its good temperateness, as are that of Mars and that of Saturn; whence Ptolemy says, in the book cited, that Jupiter is a star of a temperate complexion, midway between the coldness of Saturn and the heat of Mars. The second is, that among all the stars it shows itself white, almost silvery. And these two things are in Geometry. Geometry moves between two opposites; as between the point and the circle (and I call in general everything round, whether a solid or a surface, a circle); for, as Euclid says, the point is the beginning of Geometry, and, as he says, the circle in its most perfect figure, and may therefore be considered its end; so that between the point and the circle, as between beginning and end, Geometry moves. And these two are opposed to its exactness; for the point, on account of its indivisibility, is immeasurable; and the circle, on account of its arc, it is impossible to square, and therefore it is impossible to measure it exactly. And moreover Geometry is very white, inasmuch as it is without spot of error, and very exact in itself and its handmaiden, which is called Perspective.”