City of God

The bodies of the righteous, then, such as they shall be in the resurrection, shall need neither any fruit to preserve them from dying of disease or the wasting decay of old age, nor any other physical nourishment to allay the cravings of hunger or of thirst; for they shall be invested with so sure and every way inviolable an immortality, that they shall not eat save when they choose, nor be under the necessity of eating, while they enjoy the power of doing so. For so also was it with the angels who presented themselves to the eye and touch of men, not because they could do no otherwise, but because they were able and desirous to suit themselves to men by a kind of manhood ministry.

For neither are we to suppose, when men receive them as guests, that the angels eat only in appearance, though to any who did not know them to be angels they might seem to eat from the same necessity as ourselves. So these words spoken in the Book of Tobit, “You saw me eat, but you saw it but in vision;” that is, you thought I took food as you do for the sake of refreshing my body. But if in the case of the angels another opinion seems more capable of defence, certainly our faith leaves no room to doubt regarding our Lord Himself, that even after His resurrection, and when now in spiritual but yet real flesh, He ate and drank with His disciples; for not the power, but the need, of eating and drinking is taken from these bodies.

And so they will be spiritual, not because they shall cease to be bodies, but because they shall subsist by the quickening spirit.