Jamieson, Fausset and Brown on Daniel 8:27

27. I ... was sick--through grief at the calamities coming on my people and the Church of God (compare Psa 102:14).

afterward I ... did the king's business--He who holds nearest communion with heaven can best discharge the duties of common life.

none understood it--He had heard of kings, but knew not their names; He foresaw the events, but not the time when they were to take place; thereupon he could only feel "astonished," and leave all with the omniscient God [Jerome].