To the medieval thinker beauty was not a value independent of others, but rather the radiance of truth, the splendor of ontological perfection, and that quality of things which reflects their origin in God. Light and luminous objects, no less than musical consonance, conveyed an insight into the perfection of the cosmos, and a divination of the Creator.
It takes practice to spot angelic presences. But practice alone is not enough, unless one can practice being taken by surprise.