Every year on Candlemas/Feast of the Presentation, you can get candles blessed. This is not rocket science.
And if you cannot wait until then, just go to your priest and ask him to bless your candles now.
Or you can go really old school and put out olive oil lamps…
But fires burned perfectly well during the three days of darkness plague in Egypt. It was just that there was no darkness where the children of Israel were, so no need for special lighting.
- Back in the day, it was common for people to get a fair number of candles blessed on Candlemas, and then use them during storms or dangerous sicknesses in the household, as a form of prayer. It was also common to save baptismal candles and burn them in times of danger or on important occasions. So basically, this kind of revelation seems to be saying that the three days of darkness are at least as bad as, say, a bad thunderstorm or hurricane, but maybe not bad enough to haul out the baptismal candles.
** One Polish title of Mary translates as “Our Lady of the Thunder Candle.”
*** Actually, our Jewish brothers and sisters do have a tradition that Egyptian fire did not stay lit during the plague of darkness, but that was following a Jewish tradition that it was a Nile peasoup fog making it dark. Fires went out because the air was so humid that condensation doused them, but the fog stayed away from where the Jews were.
There’s another theory from Rabbeinu Bechaye that light and fire were working just fine, but that the photons were prevented from reaching the eyes of the Egyptians, or that the air was made so thick that photons couldn’t get through and people could not “rise from their places.” A similar theory was that it was just Egyptian bodies, eyes, or brains being affected, because the Jews could see and move just fine.
In these cases, the blessed candle thing would be pictured as just providing a sign, of God protecting and excepting from such a “darkness,” those who acknowledge Him as Lord of Creation.