Here, then, is the singular consolation which we derive from the Supper. It directs and leads us to the cross of Jesus Christ and to his resurrection, to certify to us that whatever iniquity there may be in us, the Lord nevertheless recognizes and accepts us as righteous — whatever materials of death may be in us, he nevertheless gives us life — whatever misery may be in us, he nevertheless fills us with all felicity. Or to explain the matter more simply — as in ourselves we are devoid of all good, and have not one particle of what might help procure salvation, the Supper is an attestation that, having been made partakers of the death and passion of Jesus Christ, we have every thing that is useful and salutary to us.
We can therefore say, that in it the Lord displays to us all the treasures of his spiritual grace, inasmuch he associates us in all the blessings and riches of our Lord Jesus. Let us recollect, then, that the Supper is given us as a mirror in which we may contemplate Jesus Christ crucified in order to deliver us from condemnation, and raised again in order to procure for us righteousness and eternal life. It is indeed true that this same grace is offered us by the gospel, yet as in the Supper we have more ample certainty, and fuller enjoyment of it, with good cause do we recognize this fruit coming from it.
— John Calvin, Short Treatise on the Holy Supper of Our Lord Jesus Christ, 1540.