Daniel received the Holy Spirit and therefore prophesied. So, too, the king promoted him because he had the grace of the Spirit. For the king spoke in this regard, “I have heard of you that the Spirit of the holy God is in you.” And farther on it is written, “Then Daniel became distinguished above all the other presidents and satraps, because an excellent spirit was in him.” And the spirit of Moses also was shared by those who were to be judges.
Verse 1. "It pleased Darius to appoint over his kingdom one hundred and twenty satraps, that they might be throughout his whole kingdom; and over them there were three princes, of which Daniel was one." Josephus, of whom we made mention above, in writing an account of this passage, put it this way: Now Darius, who destroyed the empire of the Babylonians in cooperation with his relative, Cyrus, - for they carried on the war as allies - was sixty-two years of age at the time he captured Babylon. He was the son of Astyages, and was known to the Greeks by another name. Moreover he took away the prophet Daniel with him and took him to Media, and made him one of the three princes who were in charge of his whole kingdom. Hence we see that when Babylon was overthrown, Darius returned to his own kingdom in Media, and brought Daniel along with him in the same honorable capacity to which he had been promoted by Belshazzar. There is no doubt but what Darius had heard of the sign and portent which had come to Belshazzar, and also of the interpretation which Daniel had set forth, and how he had foretold the rule of the Medes and the Persians. And so no one should be troubled by the fact that Daniel is said in one place to have lived in Darius's reign, and in another place in the reign of Cyrus. The Septuagint rendered Darius by the name Artaxerxes. But as for the fact that a non-chronological order is followed, so that some history is narrated in the reign of Darius before material is given for Belshazzar's reign, whereas we are subsequently to read that he was put to death by Darius, it seems to me that the anachronism results from the fact that the author has brought all the historical portions together in immediate sequence. Therefore it is at the close of the earlier vision that he had stated: "And Darius the Mede succeeded to the realm at the age of sixty-two." And so it was under this Darius who put Belshazzar to death that the events took place of which we are about to speak.
We need to take notice that previously the Babylonians, that is, their princes, had used trickery in their jealousy of Daniel to destroy Daniel and his companions and had persuaded Nebuchadnezzar to build the golden statue and to order that it alone be worshiped by those under his authority. So, too, now the Medes use trickery in the elaboration of the edict and decree in order to destroy Daniel.
[AD 397] Ambrose of Milan on Daniel 6:1