John 6:50

"This is the bread which cometh down from heaven." Manna signified this bread; God's altar signified this bread. Those were sacraments. In the signs they were diverse; in the thing which was signified they were alike. Hear the apostle: "For I would not that ye should be ignorant, brethren," saith he, "that all our fathers were under the cloud, and all passed through the sea; and were all baptized unto Moses in the cloud and in the sea; and did all eat the same spiritual meat." Of course, the same spiritual meat; for corporally it was another: since they ate manna, we eat another thing; but the spiritual was the same as that which we eat. But "our" fathers, not the fathers of those Jews; those to whom we are like, not those to whom they were like. Moreover he adds: "And did all drink the same spiritual drink." They one kind of drink, we another, but only in the visible form, which, however, signified the same thing in its spiritual virtue. For how was it that they drank the "same drink"? "They drank," saith he "of the spiritual Rock that followed them, and that Rock was Christ." Thence the bread, thence the drink. The rock was Christ in sign; the real Christ is in the Word and in flesh. And how did they drink? The rock was smitten twice with a rod; the double smiting signified the two wooden beams of the cross. "This, then, is the bread that cometh down from heaven, that if any man eat thereof, he shall not die." But this is what belongs to the virtue of the sacrament, not to the visible sacrament; he that eateth within, not without; who eateth in his heart, not who presses with his teeth.

(Tr. xxvi. s. 12) This was the bread the manna typified, this was the bread the altar typified. Both the one and the other were sacraments, differing in symbol, alike in the thing signified. Hear the Apostle, They did all eat the same spiritual meat. (1 Cor. 10)

Therefore I say, He that eateth this bread, dieth not: I am the living bread which came down from heaven.

And observe how He distinguisheth between His bread and the manna, by causing them to hear the result of each kind of food. For to show that the manna afforded them no unusual advantage, He added, "Your fathers did eat manna in the wilderness, and are dead." He then establisheth a thing most likely to persuade them, that they were deemed worthy of greater things than their fathers, (meaning those marvelous men who lived in the time of Moses,) and so, after saying that they were dead who ate the manna, He addeth, "He that eateth of this bread, shall live for ever." Nor hath He put "in the wilderness" without a cause, but to point out that the supply of manna was not extended to a long time, nor entered with them into the land of promise. But this "bread" was not of the same kind.

(Hom. xlvi. 2) The addition, In the wilderness, is not put in without meaning, but to remind them how short a time the manna lasted; only till the entrance into the land of promise. And because the bread which Christ gave seemed inferior to the manna, in that the latter had come down from heaven, while the former was of this world, He adds, This is the bread which cometh down from heaven.