John Calvin’s Institutes of Christian Religion 4.17.2-3

From this sacrament pious souls may derive the benefit of considerable satisfaction and confidence; because it affords us a testimony that we are incorporated into one body with Christ, so that whatever is his, we are at liberty to call ours. The consequence of this is, that we venture to assure our- selves of our interest in eternal life, of which he is the heir, and that the kingdom of heaven, into which he has already entered, can no more be lost by us than by him: and, on the other hand, that we cannot be condemned by our sins, from the guilt of which he absolved us, when he wished them to be im- Puted to himself, as if they were his own. This is the wonder- ful exchange which, in his infinite goodness, he has made with us. Submitting to our poverty, he has transferred to us his riches; assuming our weakness, he has strengthened us by his power; accepting our mortality, he has conferred on us his immortality; taking on himself the load of iniquity with which we were oppressed, he has clothed us with his righteousness; descending to the earth, he has prepared a way for our ascending to heaven; becoming with us the Son of man, he has made us, with himself, the sons of God.

III. Of all these things we have such a complete attestation in this sacrament, that we may confidently consider them as truly exhibited to us, as if Christ himself were presented to our eyes, and touched by our hands. For there can be no falsehood or illusion in this word, “Take, eat, drink; this is my body which is given for you; this is my blood which is shed for the remission of sins.” By commanding us to take, he signifies that he is ours: by commanding us to eat and drink, he signifies that he is become one substance with us. In saying that his body is given for us, and his blood shed for us, he shews that both are not so much his as ours, because he assumed and laid down both, not for his own advantage, but for our salvation. And it ought to be carefully observed, that the principal and almost entire energy of the sacrament lies in these words; “Which is given for you;—which is shed for you:” for otherwise it would avail us but little, that the body and blood of the Lord are distributed to us now, if they had not been once delivered for our redemption and salvation. Therefore they are represented to us by bread and wine, to teach us that they are not only ours, but are destined for the support of our spiritual life. This is what we have already suggested; that by the corporeal objects which are presented in the sacrament, we are conduced, by a kind of analogy, to those which are spiritual. So, when bread is given to us as a symbol of the body of Christ, we ought immediately to conceive of this comparison, that, as bread nourishes, sustains, and preserves the life of the body; so the body of Christ is the only food to animate and support the life of the soul. When we see wine presented as a symbol of his blood, we ought to think of the uses of wine to the human body, that we may contemplate the same advantages conferred upon us in a spiritual manner by the blood of Christ: which are these, that it nourishes, refreshes, strengthens, and exhilarates. For if we duly consider the benefits resulting to us from the oblation of his sacred body, and the effusion of his blood, we shall clearly perceive that these properties of bread and wine, according to this analogy, are most justly attributed to those symbols, as ad- ministered to us in the Lord’s Supper.