8 Then, finally, that the Scriptures were written by the Spirit of God, and have a meaning, not such only as is apparent at first sight, but also another, which escapes the notice of most. For those (words) which are written are the forms of certain mysteries, and the images of divine things. Respecting which there is one opinion throughout the whole Church, that the whole law is indeed spiritual; but that the spiritual meaning which the law conveys is not known to all, but to those only on whom the grace of the Holy Spirit is bestowed in the word of wisdom and knowledge.
The term ἀσώματον, i.e., incorporeal, is disused and unknown, not only in many other writings, but also in our own Scriptures. And if any one should quote it to us out of the little treatise entitled The Doctrine of Peter, in which the Saviour seems to say to His disciples, “I am not an incorporeal demon,” I have to reply, in the first place, that that work is not included among ecclesiastical books; for we can show that it was not composed either by Peter or by any other person inspired by the Spirit of God. But even if the point were to be conceded, the word ἀσώματον there does not convey the same meaning as is intended by Greek and Gentile authors when incorporeal nature is discussed by philosophers. For in the little treatise referred to he used the phrase “incorporeal demon” to denote that that form or outline of demoniacal body, whatever it is, does not resemble this gross and visible body of ours; but, agreeably to the intention of the author of the treatise, it must be understood to mean that He had not such a body as demons have, which is naturally fine, and thin as if formed of air (and for this reason is either considered or called by many incorporeal), but that He had a solid and palpable body. Now, according to human custom, everything which is not of that nature is called by the simple or ignorant incorporeal; as if one were to say that the air which we breathe was incorporeal, because it is not a body of such a nature as can be grasped and held, or can offer resistance to pressure.
Source: De Principiis (New Advent)