ht to be a luminous body in act--in
other words, to be fire, the noblest of the four elements.

Reply Obj. 2: Aristotle pronounces light to be fire existing in its
own proper matter: just as fire in aerial matter is "flame," or in
earthly matter is "burning coal." Nor must too much attention be paid
to the instances adduced by Aristotle in his works on logic, as he
merely mentions them as the more or less probable opinions of various
writers.

Reply Obj. 3: All these properties are assigned to light
metaphorically, and might in the same way be attributed to heat. For
because movement from place to place is naturally first in the order
of movement as is proved _Phys._ viii, text. 55, we use terms
belonging to local movement in speaking of alteration and movement of
all kinds. For even the word distance is derived from the idea of
remoteness of place, to that of all contraries, as is said _Metaph._
x, text. 13.
_______________________

THIRD ARTICLE [I, Q. 67, Art. 3]

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withdrawn.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.

Obj. 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.

Obj. 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.

_On the contrary,_ Damascene (De Fide Orth. i) says that light is a
species of quality.

_I answer that,_ Some writers have said that the light in the air has
not a natural being such as the color on a wall has, but only an
intentional being, as a similitude of color in the air. But this
cannot be the case for two reasons. First, because light gives a name
to the air, since by it the air becomes actually luminous. But color
does not do this, for we do not speak of the air as colored. Secondly,
because light produces natural effects, for by the rays of the sun
bodies are warm