Dante looks into Beatrice's eyes and sees in them the reflection of a point of light — so intense, so small, so piercing that the eye must look away. He turns to see the source directly. There: a single point, infinitely bright, surrounded by nine circles of fire spinning around it, each one faster and brighter the closer to the central point. This is the structure of the angelic hierarchy — the nine orders of angels circling God, the speed and brilliance of each order corresponding to its degree of participation in divine love.
But wait — in the physical universe, the largest and fastest sphere (the Primum Mobile) is the outermost. Here, in this vision, it is the innermost circle that is largest and fastest. The geometry is inverted. Beatrice explains: in the physical universe, the outer spheres move more because they receive more divine influence distributed across their greater size; here, the inner circles are closest to the divine source and receive it most directly and intensely. The physical universe is a shadow image of this spiritual original, and its dimensions correspond to it inversely. The more divine love a circle carries, the faster it moves, the brighter it blazes — and the innermost circle carries the most. The cosmological inversion is also a moral one: what is great by proximity to God is inwardly small by external measure.