Rorate Caeli is Latin for “Drop down, ye heavens” and are the opening words of the Introit (which is an opening psalm or antiphon), coming from Isaiah 45:8.
“Rorate, caeli, desuper, et nubes pluant justum, aperiatur terra, et germinet Salvatorem.”
“Drop down dew, ye heavens, from above, and let the clouds rain the just: let the earth be opened and bud forth a Savior.” – Isaiah 45:8
A Rorate Caeli Mass is traditionally celebrated just before dawn in Advent as a devotion to the Blessed Virgin Mary. The Mass is only lit by candles, representing Mary’s role in bringing the Light of the World into the darkness of the world.