For if we see that the sun, in sending forth its rays upon the earth, to generate, cherish, and invigorate its offspring, in a manner transfuses its substance into it, why should the radiance of the Spirit be less in conveying to us the communion of his flesh and blood? Wherefore the Scripture, when it speaks of our participation with Christ, refers its whole efficacy to the Spirit. Instead of many, one passage will suffice. Paul, in the Epistle to the Romans (Rom. 8:9-11), shows that the only way in which Christ dwells in us is by his Spirit. By this, however, he does not take away that communion of flesh and blood of which we now speak, but shows that it is owing to the Spirit alone that we possess Christ wholly, and have him abiding in us.

Institutes of the Christian Religion