Alcuin of York — on Rev 10:10 (COMMENTARY ON REVELATION)

“And I took the book from the hand of the angel, and ate it up: and it was in my mouth, sweet as honey: and when I had eaten it, my belly was bitter. It is right for the mouth, out of which preaching emanates, to represent those who meditate on God's law day and night and say with the Psalmist, How sweet are thy words to my palate! [Ps. 118:103] On the other hand, it is right for the belly, out of which excrements come, to represent fleshly people devoted to earthly pleasures, about whom the elect say, Our belly cleaveth to the earth. [Ps. 43:25] Therefore it is as if food came down through the mouth into the belly, when knowledge of the Scriptures comes through the Church's preachers even to those who live in a fleshly manner. This is why the book, which is sweet in the mouth, becomes bitter in the belly; for what can be more bitter to them than what the Lord commands, Thou shalt not covet thy neighbour's wife, nor anything that is his? [Deut. 5:21] Alternatively, the book is sweet in the mouth when eternal joys are promised in it to readers, like The just shall shine as the sun; [Matt. 13:43] but in the belly, that is in the secret of the mind, it is bitter, since one is confronted in it with strict commandments, like Unless you become as this little child, you shall not enter into the kingdom of heaven. [Variant of Matt. 18:3]”