1 Corinthians 10:4

4.That rock was Christ Some absurdly pervert these words of Paul, as if he had said, that Christ was the spiritual rock, and as if he were not speaking of that rock which was a visible sign, for we see that he is expressly treating of outward signs. The objection that they make — that the rock is spoken of as spiritual, is a frivolous one, inasmuch as that epithet is applied to it simply that we may know that it was a token of a spiritual mystery. In the mean time, there is no doubt, that he compares our sacraments with the ancient ones. Their second objection is more foolish and more childish — “How could a rock,” say they, “that stood firm in its place, follow the Israelites?” — as if it were not abundantly manifest, that by the word rock is meant the stream of water, which never ceased to accompany the people. For Paul extols (535) the grace of God, on this account, that he commanded the water that was drawn out from the rock to flow forth wherever the people journeyed, as if the rock itself had followed them. Now if Paul’s meaning were, that Christ is the spiritual foundation of the Church, what occasion were there for his using the past tense? (536) It is abundantly manifest, that something is here expressed that was peculiar to the fathers. Away, then, with that foolish fancy by which contentious men choose rather to show their impudence, than admit that they are sacramental forms of expression! (537)

I have, however, already stated, that the reality of the things signified was exhibited in connection with the ancient sacraments. As, therefore, they were emblems of Christ, it follows, that Christ was connected with them, not locally, nor by a natural or substantial union, but sacramentally. On this principle the Apostle says, that the rock was Christ, for nothing is more common than metonymy in speaking of sacraments. The name of the thing, therefore, is transferred here to the sign — not as if it were strictly applicable, but figuratively, on the ground of that connection which I have mentioned. I touch upon this, however, the more slightly, because it will be more largely treated of when we come to the 11th Chapter.

There remains another question. “Seeing that we now in the Supper eat the body of Christ, and drink his blood, how could the Jews be partakers of the same spiritual meat and drink, when there was as yet no flesh of Christ that they could eat?” I answer, that though his flesh did not as yet exist, it was, nevertheless, food for them. Nor is this an empty or sophistical subtilty, for their salvation depended on the benefit of his death and resurrection. Hence, they required to receive the flesh and the blood of Christ, that they might participate in the benefit of redemption. This reception of it was the secret work of the Holy Spirit, who wrought in them in such a manner, that Christ’s flesh, though not yet created, was made efficacious in them. He means, however, that they ate in their own way, which was different from ours, (538) and this is what I have previously stated, that Christ is now presented to us more fully, according to the measure of the revelation. For, in the present day, the eating is substantial, which it could not have been then — that is, Christ feeds us with his flesh, which has been sacrificed for us, and appointed as our food, and from this we derive life.