Then this Daniel was preferred above the presidents and princes, because an excellent spirit was in him; and the king thought to set him over the whole realm.
Daniel was preferred above the presidents and princes, because an excellent spirit was in him - probably because of his having so wonderfully foretold the fall of Babylon. Hence, the very expression used by the queen-mother on that occasion (Daniel 5:12) is here used, "because an excellent spirit was in him."
And the king thought to set him over the whole realm - agreeing with Darius' character, weak, and averse to business, which he preferred to delegate to favourites. God overruled this to the good both of Daniel, and, through him, of His people.