Of Prayer, by John Calvin, tr. Henry Beveridge , at sacred-texts.com
And we must carefully attend to the circumstance of time. Christ enjoins his disciples to have recourse to his intercession after he shall have ascended to heaven: "At that day ye shall ask in my name" (John 16:26). It is certain, indeed, that from the very first all who ever prayed were heard only for the sake of the Mediator. For this reason God had commanded in the Law, that the priest alone should enter the sanctuary, bearing the names of the twelve tribes of Israel on his shoulders, and as many precious stones on his breast, while the people were to stand at a distance in the outer court, and thereafter unite their prayers with the priest. Nay, the sacrifice had even the effect of ratifying and confirming their prayers. That shadowy ceremony of the Law therefore taught, first, that we are all excluded from the face of God, and, therefore, that there is need of a Mediator to appear in our name, and carry us on his shoulders and keep us bound upon his breast, that we may be heard in his person; And secondly, that our prayers, which, as has been said, would otherwise never be free from impurity, are cleansed by the sprinkling of his blood. And we see that the saints, when they desired to obtain anything, founded their hopes on sacrifices, because they knew that by sacrifice all prayers were ratified: " Remember all thy offerings," says David, "and accept thy burnt sacrifice" (Psalm 20:3). Hence we infer, that in receiving the prayers of his people, God was from the very first appeased by the intercession of Christ. Why then does Christ speak of a new period ("at that day") when the disciples were to begin to pray in his name, unless it be that this grace, being now more brightly displayed, ought also to be in higher estimation with us? In this sense he had said a little before, "Hitherto ye have asked nothing in my name; ask." Not that they were altogether ignorant of the office of Mediator (all the Jews were instructed in these first rudiments), but they did not clearly understand that Christ by his ascent to heaven would be more the advocate of the Church than before. Therefore, to solace their grief for his absence by some more than ordinary result, he asserts his office of advocate, and says, that hitherto they had been without the special benefit which it would be their privilege to enjoy, when aided by his intercession they should invoke God with greater freedom. In this sense the Apostle says that we have "boldness to enter into the holiest by the blood of Jesus, by a new and living way, which he hath consecrated for us" (Heb. 10:19, 20). Therefore, the more inexcusable we are, if we do not with both hands (as it is said) embrace the inestimable gift which is properly destined for us.