John Calvin on Daniel 5:31

Daniel adds, the kingdom was transferred to the king of the Medes, whom he calls Darius, but Xenophon terms him Cyaxares. It is clear enough that Babylon was taken by the skill and under the auspices of Cyrus; since he was a persevering warrior possessed of great authority, though he is not mentioned here. But since Xenophon relates that Cyaxares, here called Darius, was Cyrus’s father-in-law, and thus held in the highest honor and estimation, it is not surprising to find Daniel bringing that king before us. Cyrus was content with his own power and with the praise and fame of his victory, and readily conceded this title to his father-in-law, whom he perceived to be now growing aged and infirm. It is uncertain whether he was the son of Astyages, and thus the uncle of Cyrus. Many historians concur in stating that Astyages was the grandfather of Cyrus who married his daughter to Cambyses; because the astrologers had informed him how an offspring should be born of her who should possess the sovereignty over all Asia! Many add the story of his ordering the infant Cyrus to be slain, but since these matters are uncertain, I leave them undecided. I rather think Darius was the uncle of Cyrus, and also his father-in-law; though, if we believe Xenophon, he was unmarried at the capture of Babylon; for his uncle, and perhaps his father-in-law, had sent him to bring supplies when he was inferior in numbers to the Babylonians and Assyrians. However this may be, the Prophet’s narrative suits the circumstances well enough, for Darius, as king of the Medes, obtained the royal authority. Cyrus was, indeed, higher than he in both rank and majesty, but he granted him the title of King of Babylon, and under this name he reigned over the Chaldeans. It now follows, —

CHAPTER 6

Daniel 6:1-2

1. It pleased Darius to set over the kingdom an hundred and twenty princes, which should be over the whole kingdom;

1. Placuit coram Dario, et praefecit super regnum praesides provinciarum centum et viginti, qui essent in toto regno.

2. And over these three presidents; of whom Daniel was first: that the princes might give accounts unto them, and the king should have no damage.

2. Et super illos essent, atque ut essent super eos, satrapae tres, quorum Daniel unus esset: et ut praesides provinciarum illis redderent rationem: et rex non pateretur damnum.