It is hence clear, that the same fire will be appropriated to the punishment of men and of daemons. If then it inflicts pain by corporeal touch, so as to produce bodily torment, how will there be in it any punishment for the evil spirits, unless the daemons have, as some have thought, bodies composed of gross and fluid air. But if any man asserts that the daemons have no bodies, we would not pugnaciously contend the point. For why may we not say, that truly, though wonderfully, even incorporeal spirit can feel pain of corporeal fire? If the spirits of men, though themselves incorporeal, can be now inclosed in bodily limbs, they can then be inseparably attached to the bonds of body. The daemons then will be united to a body of material fire, though themselves immaterial, drawing punishment from their body, not giving life to it. And that fire being material will torture such bodies as ours with their spirits; but the daemons are spirits without bodies.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: City of God, xxi, 10