c. 206–207 · Tertullian, On the Resurrection of the Flesh (De resurrectione carnis) 37
He says, it is true, that “the flesh profiteth nothing;” but then, as in the former case, the meaning must be regulated by the subject which is spoken of. Now, because they thought His discourse was harsh and intolerable, supposing that He had really and literally enjoined on them to eat his flesh, He, with the view of ordering the state of salvation as a spiritual thing, set out with the principle, “It is the spirit that quickeneth;” and then added, “The flesh profiteth nothing,”—meaning, of course, to the giving of life. He also goes on to explain what He would have us to understand by spirit: “The words that I speak unto you, they are spirit, and they are life.” In a like sense He had previously said: “He that heareth my words, and believeth on Him that sent me, hath everlasting life, and shall not come into condemnation, but shall pass from death unto life.” Constituting, therefore, His word as the life-giving principle, because that word is spirit and life, He likewise called His flesh by the same appellation; because, too, the Word had become flesh, we ought therefore to desire Him in order that we may have life, and to devour Him with the ear, and to ruminate on Him with the understanding, and to digest Him by faith.