Today was the feast of St. Gregory the Great, also known as St. Gregory the Dialogist, Pope and Doctor of the Church. From Book IV of his Dialogues (Chapter 59):
And here also we have diligently to consider, that it is far more secure and safe that every man should do that for himself whiles he is yet alive, which he desireth that others should do for him after his death. For far more blessed it is, to depart free out of this world, than being in prison to seek for release: and therefore reason teacheth us, that we should with our whole soul contemn this present world, at least because we see that it is now gone and past: and to offer unto God the daily sacrifice of tears, and the daily sacrifice of his body and blood. For this sacrifice doth especially save our souls from everlasting damnation, which in mystery doth renew unto us the death of the Son of God: who although being risen from death, doth not now die any more, nor death shall not any further prevail against him: yet living in himself immortally, and without all corruption, he is again sacrificed for us in this mystery of the holy oblation: for there his body is received, there his flesh is distributed for the salvation of the people: there his blood is not now shed betwixt the hands of infidels, but poured into the mouths of the faithful. Wherefore let us hereby meditate what manner of sacrifice this is, ordained for us, which for our absolution doth always represent the passion of the only Son of God: for what right believing Christian can doubt, that in the very hour of the sacrifice, at the words of the Priest, the heavens be opened, and the quires of Angels are present in that mystery of Jesus Christ; that high things are accompanied with low, and earthly joined to heavenly, and that one thing is made of visible and invisible?
