 Geometrical figures are used early in Book 1 of On Learned Ignorance to illustrate how our knowledge of created things is only approximative. A bit later we are led to extrapolate straight and curved lines as an aid to understanding the coincidence of opposites and to moving human thought towards the God who is unknowable by reason. Book 2 uses number to illustrate enfolding and unfolding—as the number series unfolds what is enfolded in the unit, so God unfolds all created things. Nicholas later introduces the geometrical image of the sphere whose center is everywhere and whose circumference is nowhere to explain how the physical universe’s lack of boundaries is an image of God’s infinity. Book 2 also opens and closes with reflection on the quadrivium: arithmetic, geometry, music and astronomy. Book 3 returns to the image of the infinite sphere for the combination of absolute and contracted reality in the God-man.