Calvin: the wonderful exchange
Godly souls can gather great assurance and delight from this Sacrament [of the Lord’s Supper]; in it they have a witness of our growth into one body with Christ such that whatever is his may be called ours. As a consequence, we may dare assure ourselves that eternal life, of which he is the heir, is ours; and that the Kingdom of Heaven, into which he has already entered, can no more be cut off from us than from him; again, that we cannot be condemned for our sins, from whose guilt he has absolved us, since he willed to take them upon himself as if they were his own. This is the wonderful exchange which, out of his measureless benevolence, he has made with us; that, becoming Son of man with us, he has made us sons of God with him; that, by his descent to earth, he has prepared an ascent to heaven for us; that, by taking on our mortality, he has conferred his immortality upon us; that, accepting our weakness, he has strengthened us by his power; that, receiving our poverty unto himself, he has transferred his wealth to us; that, taking the weight of our iniquity upon himself (which oppressed us), he has clothed us with his righteousness.
—John Calvin, Institutes of the Christian Religion, Book IV, Ch. 17.2.