19 And Gideon went in, and made ready a kid, and unleavened cakes of an ephah of flour: the flesh he put in a basket, and he put the broth in a pot, and brought it out unto him under the oak, and presented it.
And Gideon, moved by that message, when he heard that, though thousands of the people failed, God would deliver His own from their enemies by means of one man, offered a kid, and according to the word of the Angel, laid its flesh and the unleavened cakes upon the rock, and poured the broth upon them. And as soon as the Angel touched them with the end of the staff which he bore, fire burst forth out of the rock, and so the sacrifice which he was offering was consumed. By which it seems clear that that rock was a figure of the Body of Christ, for it is written: "They drank of that rock that followed them, and that rock was Christ." Which certainly refers not to His Godhead, but to His Flesh, which watered the hearts of the thirsting people with the perpetual stream of His Blood.
Even at that time was it declared in a mystery that the Lord Jesus in His Flesh would, when crucified, do away the sins of the whole world, and not only the deeds of the body, but the desires of the soul. For the flesh of the kid refers to sins of deed, the broth to the enticements of desire as it is written: "For the people lusted an evil lust, and said, Who shall give us flesh to eat?" That the Angel then stretched forth his staff, and touched the rock, from which fire went out, shows that the Flesh of the Lord, being filled with the Divine Spirit, would burn away all the sins of human frailty. Wherefore, also, the Lord says: "I am come to send fire upon the earth."
"But I say unto you, that whosoever looketh on a woman to lust after her, hath committed adultery with her already in his heart." "The humour," therefore, "is wiped off," when sin is not only severed from the deed, but also from the thought. It is hence that Jerubbaal saw the Angel when he was winnowing corn from the chaff, at whose bidding he forthwith dressed a kid and set it upon a rock, and poured over it the broth of the flesh, which the Angel touched with a rod, and thereupon fire coming out of the rock consumed it. For what else is it to beat corn with a rod, but to separate the grains of virtues from the chaff of vices, with an upright judgment? But to those that are thus employed the Angel presents himself, in that the Lord is more ready to communicate interior truths in proportion as men are more earnest in ridding themselves of external things. And he orders a kid to be killed, i.e. every appetite of the flesh to be sacrificed, and the flesh to be set upon a rock, and the broth thereof to be poured upon it. Whom else does the "rock" represent, saving Him, of Whom it is said by Paul, "And that rock was Christ"? We "set flesh then upon the rock," when in imitation of Christ we crucify our body. He too pours the juice of the flesh over it, who, in following the conversation of Christ, empties himself even of the mere thoughts of the flesh themselves. For "the broth" of the dissolved flesh is in a manner "poured upon the rock," when the mind is emptied of the flow of carnal thoughts too. Yet the Angel directly touches it with a rod, in that the might of God's succour never leaves our striving forsaken. And fire issues from the rock, and consumes the broth and the flesh, in that the Spirit, breathed upon us by the Redeemer, lights up the heart with so fierce a flame of compunction, that it consumes every thing in it that is unlawful either in deed or in thought.
[AD 397] Ambrose of Milan on Judges 6:19-21
Even at that time was it declared in a mystery that the Lord Jesus in His Flesh would, when crucified, do away the sins of the whole world, and not only the deeds of the body, but the desires of the soul. For the flesh of the kid refers to sins of deed, the broth to the enticements of desire as it is written: "For the people lusted an evil lust, and said, Who shall give us flesh to eat?" That the Angel then stretched forth his staff, and touched the rock, from which fire went out, shows that the Flesh of the Lord, being filled with the Divine Spirit, would burn away all the sins of human frailty. Wherefore, also, the Lord says: "I am come to send fire upon the earth."