John Chrysostom

For Christ offered His blood to him who betrayed Him, that he might have remission of his sins, if he had chosen to cease to be wicked.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

He called His Blood the Blood of the "New Testament," in distinction from the Old Testament, for the Old Testament also had blood, with which both the people and the books of the Law were sprinkled.

Commentary on Mark ↗

Clement of Alexandria

In what manner do you think the Lord drank when He became man for our sakes? As shamelessly as we? Was it not with decorum and propriety? Was it not deliberately? For rest assured, He Himself also partook of wine; for He, too, was man. And He blessed the wine, saying, "Take, drink: this is my blood"-the blood of the vine. He figuratively calls the Word "shed for many, for the remission of sins"-the holy stream of gladness. And that he who drinks ought to observe moderation, He clearly showed by what He taught at feasts.

The Instructor Book 2 ↗

Ambrose of Milan

Jesus himself speaks of his blood. Before the consecration it is mentioned as something else; after the consecration it is called blood. And you say "Amen," that is, "It is true." Let the mind within confess what the mouth speaks. Let the heart feel what the words utter.

On the Mysteries 1 ↗

Bede

And he said to them: This is my blood of the new testament, which shall be shed for many. Because bread strengthens the body, but wine works blood in the flesh: this is mystically related to the body of Christ, that refers to the blood. But because it is necessary that both we remain in Christ, and Christ in us, water is mixed with the wine of the Lord's cup. For according to John, the waters are the peoples. …

On the Gospel of Mark ↗