John Calvin Commentary Numbers 23:4

"And God met Balaam: and he said unto him, I have prepared the seven altars, and I have offered up a bullock and a ram on every altar." — Numbers 23:4 (ASV)

And God met Balaam. It is astonishing that God should have determined to have anything in common with the pollutions of Balaam, since there is no communion between light and darkness, and He detests all association with demons; but, however hateful Balaam's impiety was to God, this did not prevent Him from making use of him in this particular act. This meeting him, then, was by no means a proof of His favor, as if He approved of the seven altars and sanctioned these superstitions. Instead, just as He knows well how to apply corrupt instruments to His use, so by the mouth of this false prophet, He promulgated the covenant He had made with Abraham to foreign and heathen nations.

In truth, Balaam boasts of his seven altars, as if he had duly propitiated God. Thus hypocrites arrogantly trust that they deserve well from God when they only provoke His anger. God, however, passes over this corrupt worship and proceeds with what He had determined, for He sends Balaam to be a proclaimer and witness of the sureness of His grace toward His chosen people.

Indeed, God supplies His servants with what they speak and controls their tongues, for they would not be sufficient to think anything unless He bestowed the ability; and no one can say that Jesus is the Lord but by the Holy Ghost.

Still, the holy Prophets were organs of the Spirit in such a way that they brought forth from the heart the treasures God had deposited with them. In this view, Jeremiah says that he did eat the words of God (Jeremiah 15:16), and Ezekiel, that he ate the roll on which his prophecies were written (Ezekiel 3:1).

For we must not conceive an inspiration (ἐνθουσιασμὸς) like that by which the heathens supposed their diviners to be carried away, so that the heavenly afflatus transported them or threw them into ecstasies. Rather, what took place in them is what David declares of himself: I believed, therefore have I spoken (Psalms 116:10). God illuminated their senses before He guided their tongues. The case of Balaam was different: his mind was alienated while he delivered the words put into his mouth.¹⁵⁶

¹⁵⁶ Addition in Fr.; “comme une pie en cage, ainsi qu’on dit;” like pie in a cage, as they say. “comme une pie en cage, ainsi qu’on dit;” like pie in a cage, as they say.