"In the sacrament he is immolated for the people not only on every Paschal Solemnity but on every day; and a man would not be lying if, when asked, he were to reply that Christ is being immolated. For if sacraments had not a likeness to those things of which they are sacraments, they would not be sacraments at all; and they generally take the names of those same things by reason of this likeness."
Letters 98:9 [A.D. 412])
"For when he says in another book, which is called Ecclesiastes, 'There is no good for a man except that he should eat and drink' [Eccl. 2:24], what can he be more credibly understood to say [prophetically] than what belongs to the participation of this table which the Mediator of the New Testament himself, the priest after the order of Melchizedek, furnishes with his own body and blood? For that sacrifice has succeeded all the sacrifices of the Old Testament, which were slain as a shadow of what was to come. . . . Because, instead of all these sacrifices and oblations, his Body is offered and is served up to the partakers of it."
The City of God 17:20 [A.D. 419]