The brightness of light is nothing else than its intensity; or as we might say, its adequacy. Thus the Son is adequate, or equal, to the Father. But in these metaphors the imagination, and consequently the meaning, of the ancients who first used them, and our imagination, disciplined by modern science, continually fail to correspond. To understand the ancients, we must leave our science behind, and dwell in the prima facie region of sense and first impressions.
Of God and His Creatures: 4.12