Whether light is a quality?

❌ Objection 1 : It would seem that light is not a quality. For every quality remains in its subject, though the active cause of the quality be removed, as heat remains in water removed from the fire. But light does not remain in the air when the source of light is withdrawn. Therefore light is not a quality.

❌ Objection 2 : Further, every sensible quality has its opposite, as cold is opposed to heat, blackness to whiteness. But this is not the case with light since darkness is merely a privation of light. Light therefore is not a sensible quality.

❌ Objection 3 : Further, a cause is more potent than its effect. But the light of the heavenly bodies is a cause of substantial forms of earthly bodies, and also gives to colors their immaterial being, by making them actually visible. Light, then, is not a sensible quality, but rather a substantial or spiritual form.