Acts 2:19

I will shew wonders, &c. These prodigies are commonly expounded of those that shall forerun the last day; or of the prognostics of the destruction of Jerusalem, which was a figure of the destruction of the world. (Witham) --- Blood, fire, &c. These prodigies were accomplished at our Saviour's death, or before the destruction of Jerusalem. We must not expect in these prophecies, where the descriptions are so grand, pathetic, and hyperbolical, to find that the accomplishment of them is literal, and precisely according to terms. The sun shall suffer an eclipse, the moon turn red, like blood, &c. (Calmet)