Three days of darkness

Shortly after the peak of the persecution of the Church that is, an attempt to abolish the daily Sacrifice of the Mass—the "Eclipse of the Son"—there may come a time which mystics in the Church describe as "three days of darkness."

God will send two punishments: one will be in the form of wars, revolutions, and other evils; it shall originate on earth. The other will be sent from Heaven. There shall come over the whole earth an intense darkness lasting three days and three nights. Nothing can be seen, and the air will be laden with pestilence which will claim mainly, but not only, the enemies of religion. It will be impossible to use any man-made lighting during this darkness, except blessed candles. —Blessed Anna Maria Taigi, d. 1837

There is a precedent for such an event as found in the book of Exodus:

Moses stretched out his hand toward the sky, and there was dense darkness throughout the land of Egypt for three days. Men could not see one another, nor could they move from where they were, for three days. But all the Israelites had light where they dwelt. (10:22-23)