Of God and His Creatures

Were angels in the habit of using bodily instruments to bodily effects within the circle of our experience, we could no more call the felling of a tree by an angel with an axe 'miraculous' than the ordinary action of the woodman. Such angelic activities were scarcely regarded by St Thomas's age as extraordinary occurrences. They thought that spirits frequently meddled with sublunary things. We should count any such interference extraordinary; and if we believed it to be the interference of a good angel, acting within his own power by divine permission, we should not hesitate to call it a miracle. We have to consider, not merely what the angels can do physically, but what God allows them to do in this lower world. He seems to allow them frequently to influence men's minds, but seldom to play any part in the production of physical phenomena. It would be more true to say that angels make men their instruments than that they use material things instrumentally.

Of God and His Creatures: 3.103