The heaven of the Sun may be compared to Arithmetic because of two properties: one is that all the other stars are informed by its light; the other is that the eye cannot look at it. And these two properties are found in Arithmetic: for by its light all sciences are illuminated, because all their subjects are considered under some numerical aspect, and in considering them we always proceed by number. [...]

The other property of the Sun is also seen in number, of which Arithmetic is the science: the eye of the intellect cannot look upon it, because number insofar as it is considered in itself is infinite, and this we cannot comprehend.

Convivio II, XIII, 15-19