Calvin on the Sovereignty of God in Election and Reprobation: Book 3:23:1

"Let my readers observe that Paul, to cut off all handle for murmuring and detraction, attributes supreme sovereignty to the wrath and power of God; for it were unjust that those profound judgments, which transcend all our powers of discernment, should be subjected to our calculation."

But if they will still murmur, let us in the soberness of faith rest contented with the admonition of Paul, that it can be no ground of complaint that God, “willing to show his wrath, and to make his power known, endured with much long-suffering the vessels of wrath fitted for destruction: and that he might make known the riches of his glory on the vessels of mercy, which he had store prepared unto glory,” ( [Rom. 9:22, 23] ). Let my readers observe that Paul, to cut off all handle for murmuring and detraction, attributes supreme sovereignty to the wrath and power of God; for it were unjust that those profound judgments, which transcend all our powers of discernment, should be subjected to our calculation. It is frivolous in our opponents to reply, that God does not altogether reject those whom in levity he tolerates, but remains in suspense with regard to them, if per adventure they may repent; as if Paul were representing God as patiently waiting for the conversion of those whom he describes as fitted for destruction. For Augustine, rightly expounding this passage, says that where power is united to endurance, God does not permit, but rules (August. Cont. Julian., Lib. 5, c. 5). They add also, that it is not without cause the vessels of wrath are said to be fitted for destruction, and that God is said to have prepared the vessels of mercy, because in this way the praise of salvation is claimed for God, whereas the blame of perdition is thrown upon those who of their own accord bring it upon themselves. But were I to concede that by the different forms of expression Paul softens the harshness of the former clause, it by no means follows, that he transfers the preparation for destruction to any other cause than the secret counsel of God. This, indeed, is asserted in the preceding context, where God is said to have raised up Pharaoh, and to harden whom he will. Hence it follows, that the hidden counsel of God is the cause of hardening. I at least hold with Augustine that when God makes sheep out of wolves, he forms them again by the powerful influence of grace, that their hardness may thus be subdued, and that he does not convert the obstinate, because he does not exert that more powerful grace, a grace which he has at command, if he were disposed to use it (August. de Prædest. Sanct., Lib. 1, c. 2). 

Institutes of the Christian Religion, Book 3, Chapter 23, Section 1.