They consist in the celebration of 30 consecutive masses for the benefit of the deceased person without interruption. The origin in this pious practice comes from the Dialogues of Pope St Gregory. As St. Gregory was abbot of St. Andrew’s in Rome, he prohibited the burial in consecrated ground of a monk named Giusto because, although he had made a vow of poverty he had wrongfully kept 3 gold coins.
In the meantime however he had 30 consecutive masses said daily for him without interruption. On the thirtieth day the dead monk appeared to his brother, a monk in the same monastery, saying “until now I have suffered, but not any longer”. Thus the pious practice spread and the convictions that the soul was freed from Purgatory.
The Church has always validated this pious practice and still advises its use. Of course it does not affirm with certainty that through the celebrations that it is certain that the soul concerned is liberated from Purgatory. Having been approved by the Church however, we can nourish a lively hope that the Lord, in his goodness and mercy will wish to liberate the sold for who the thirty masses have been celebrated, each of which is of infinite value.