1 Of the holy Gospel according to John, which you see in our hand, your Charity has already heard much, whereon by God's grace we have discoursed according to our ability, pressing on your notice that this evangelist, specially, has chosen to speak of the Lord's divinity, wherein He is equal with the Father and the only Son of God; and on that account he has been compared to the eagle, because no other bird is understood to take a loftier flight. Accordingly, to what follows in order, as the Lord enables us to treat of it, listen with all your attention.
Source: Tractates on the Gospel of John (New Advent)