Matthew Poole and continuators on Daniel 10:20

20 Then said he, Knowest thou wherefore I come unto thee ? and now will I return to fight with the prince of Persia : and when I am gone forth, lo, the prince of Grecia shall come.

i. e. By what I have said already, and what I have further to tell thee upon thy prayers which God hath accepted, and hath given me in charge to reveal to thee as followeth to the end.

Cyrus, or Cambyses, who by their Counsels and Captains hinder the work of God; and to bring the Prince of Greece upon him, viz. Alexander the great, who utterly ruined the Persian Monarchy, which is ushered with the word Lo, because it was a wonder that the Prince of Greece with 30000 men should do it. Thus the Lord sets and disposeth the Fates of Empires, and changeth them as he lists: especially in his Churches quarrel.