B. What Sort of Body an Angel assumes

8. Second I say that an angel does not assume a celestial body [n.3]. Nor does he assume an elemental body in which he may appear, because he does not visibly appear in an elemental body, nor is an elemental body susceptive of the accidents in which he appears [n.3]. But mixed bodies - already generated by nature - he can assume, as the corpse of a dead man or a stone or something similar.

9. However, when he assumes some body which does not seem to have been first caused or formed by natural causes but seems to be as it were caused then and to disappear at once - complete with operation - (as was the case with Raphael and the angel appearing to Manuel [Tobit 12.21, Judges 13.20-21]), then it seems probable that the body is a mixed one, because of the accidents that appear in the body, but not mixed with full mixture, both because such a mixed body could not be suddenly formed thus by generation - and because such a body would not be of a nature to be generated save according to the determinate process of nature, and the sort of body there is not according to nature (for example, if an angel appears in the body of a man not previously generated by nature - which body would not be of a nature to be generated save in a mother). Nor can it be said that an angel at once induces the form in the matter, because he cannot induce a natural form - but all he can do is use active and passive elements together in a suitable way and put them next to each other in a place suitable to the celestial bodies, so that a particular form may be induced that is of a nature to be induced by such particular celestial agents. Therefore, a body that is as it were suddenly formed and dissolved is mixed with imperfect mixture (of the sort that can be induced suddenly as it were by natural agents, when they are brought close to the elements), such that this sort of body is more like an impression, which is something imperfectly mixed; and a sign of this comes from corruption, because, when such a body disappears, there does not remain anything of the sort of body that the assumed body would naturally be immediately resolved into if it had been perfectly mixed (for the body of a man, if it were perfectly mixed, is not of a nature to return to anything but a corpse); rather, it is resolved at once into elements, just as it was able to be immediately generated from elements because of their imperfect mixing.