12. Artaxerxes, king of kings--That title might have been assumed as, with literal truth, applicable to him, since many of the tributary princes of his empire still retained the name and authority of kings. But it was a probably a mere Orientalism, denoting a great and powerful prince, as the heaven of heavens signified the highest heaven, and vanity of vanities, the greatest vanity. This vainglorious title was assumed by the kings of Assyria, from whom it passed to the sovereigns of Persia.
      unto Ezra the priest, a scribe of the law of the God of heaven--The appointment of Ezra to this influential mission was of the highest importance to the Hebrew people, as a large proportion of them were become, in a great measure, strangers both to the language and the institutions of their forefathers.

JFB.