Alcuin of York — on Rev 6:1 (COMMENTARY ON REVELATION)

“And when the Lamb had opened one of the seven seals, I heard one of the four living creatures, as it were the voice of a great thunder, saying: Come, and see. The opening of a seal is the revelation of a mystery. Now since there is not one, but many mysteries, and it would be long to speak about every one of them individually, all of them can be encompassed in three kinds, namely one kind pertaining to speech, one pertaining to cognition, and one pertaining to action. Speech includes in itself all commandments. Cognition, when applied according to the rules, teaches us the forms of understanding. As for action, it is in harmony with both. After one of the seven seals has been opened, one of the four living creatures invites John, in the manner of a great thunder, to come and see, because, after the truth has been manifested, the Church that precedes, consisting of the apostles, calls to faith the one that follows.”