Gregory the Dialogist

Tell Me, if thou knowest all things, in what path the light dwelleth, and what is the place of darkness? that thou mayest take each of them to the bounds thereof, and understand the paths to the house thereof. Blessed Job is tried with a weighty question, in that he is examined as to the way of light and the place of darkness, whether he should bring them each to their boundaries, and should understand the paths to the house thereof. For what is understood by the word 'light' but righteousness? …

Morals on the Book of Job, Book XXIX ↗

Thomas Aquinas

When he has said these things about the action of heavenly light on lower bodies, he mentions the light itself when he says, "Tell me, if you know everything," so that you are fit to argue with God who knows everything, "in which path does light dwell?" Consider here that light is found in the heavenly bodies of the world, which are called luminaries because of the fact that they are vessels of light. But since a path refers to motion, the question of the path in which the light dwells refers to the motion of the luminaries. …

Commentary on Job ↗