Adam Clarke on Haggai 2:21

I will shake the heavens and the earth - Calmet supposes that the invasion of Cambyses, and his death, are what the prophet has in view by this shaking of the heavens and the earth: but this invasion and defeat happened three years before they had begun to work at the temple; and how could it be made a matter of interest to Zerubbabel? Calmet answers this, by translating the words in the past tense; and shows that the fact was recalled to Zerubbabel's attention, to fix his confidence in God, etc. Bp. Newcome says we may well understand this and the twenty-second verse of the calamity undergone by Babylon in the reign of Darius; of the Macedonian conquests in Persia; and of the wars which the successors of Alexander waged against each other: others under stand it of the Romans.