Bonaventure — on Rev 7:2 (Collations on the Hexaemeron, Collation 23)

“How can this be? See what is said toward the end of the Apocalypse. Toward the middle, it is said: "I saw the Lamb standing upon Mount Sion, and with Him a hundred and forty-four thousand having His name and the name of His Father written on their foreheads." But at the opening of the sixth seal, it is said in the Apocalypse: "And I saw another angel ascending from the rising of the sun, having the seal of the living God; and he cried with a loud voice to the four angels, who had it in their power to harm the earth and the sea, saying, 'Do not harm the earth or the sea or the trees, till we have sealed the servants of our God on their foreheads.' And I heard the number of those who were sealed, out of every tribe of the children of Israel; of the tribe of Juda, twelve thousand sealed," etc. The tribe of Dan is not counted, but Manasses is counted instead of Dan, and Joseph instead of Ephraim. In Deuteronomy, Simeon is omitted. This is how the contemplative soul is sealed by God. Hence, in reference to the sixth angel, it is said that an angel appeared, "having the seal of the living God." That was when Jerusalem was shown as standing in heaven. And to this angel appeared an expressive seal, as regards the manner of living in conformity with this seal, which is what was sealed: "Of the tribe of Juda, twelve thousand sealed," etc. And that is, that everyone who possesses this thrice-uplifting light must have a threefold perfection corresponding to love. Hence, to seal in this manner is to bind [oneself] to this through a promise and to impress a seal that would correspond to this seal of love.”