The emblems of this mystery are the bread and wine through which theLord holds out to us the true communication of his body and blood. We are talking of spiritual communion, which is effected by the bond of the Holy Spirit alone, and which in no way requires a presence enclosed in Christ’s flesh through the bread or his blood through the wine. For although Christ, exalted in heaven, has left behind this earthly abode in which we are still pilgrims, yet no distance can dissolve his power by which he feeds his people with himself. Although they are very far from him, by this power he grants them to enjoy a communion with himself which is nonetheless very close.
So it is that in the Supper the Lord gives us teaching which is so certain and unmistakable that we must be assured without doubt that Christ, with all his riches, is there presented to us, no less than if he were placed before our eyes and touched by our hands.
The power and efficacy of Christ are such that, in the Supper, he not only brings to our spirits an assured confidence in eternal life, but he also makes us certain of the immortality of our flesh. For our flesh is already given life by his immortal flesh and, in some way, share his immortality.John Calvin, “Truth For All Time”