Pope St. Gregory I: Whether there be any fire of purgatory in the next world

GREGORY. Our Lord saith in the Gospel: Walk while you have the light: and by his Prophet he saith: In time accepted have I heard thee, and in the day of salvation have I hope in thee: which the Apostle St. Paul expounding, saith: Behold, now is the time acceptable; behold, now the day of salvation. Solomon, likewise, saith: Whatsoever thy hand is able to do, work it instantly: for neither work, nor reason, nor knowledge, nor wisdom shall be in hell, whither thou dost hasten. David also saith: Because his mercy is for ever. By which sayings it is plain, that in such state as a man departeth out of this life, in the same he is presented in judgment before God.

But yet we must believe that before the day of judgment there is a Purgatory fire for certain small sins: because our Saviour saith, that he which speaketh blasphemy against the holy Ghost, that it shall not be forgiven him, neither in this world, nor in the world to come. Out of which sentence we learn, that some sins are forgiven in this world, and some other may be pardoned in the next: for that which is denied concerning one sin, is consequently understood to be granted touching some other. But yet this, as I said, we have not to believe but only concerning little and very small sins, as, for example, daily idle talk, immoderate laughter, negligence in the care of our family (which kind of offences scarce can they avoid, that know in what sort sin is to be shunned), ignorant errors in matters of no great weight: all which sins be punished after death, if men procured not pardon and remission for them in their lifetime: for when St. Paul saith, that Christ is the foundation: and by and by addeth: And if any man build upon this foundation gold, silver, precious stones, wood, hay, stubble: the work of every one, of what kind it is, the fire shall try. If any man's work abide which he built thereupon, he shall receive reward; if any mans work burn, he shall suffer detriment, but himself shall be saved, yet so as by fire. For although these words may be understood of the fire of tribulation, which men suffer in this world: yet if any will interpret them of the fire of Purgatory, which shall be in the next life: then must he carefully consider, that the Apostle said not that he may be saved by fire, that buildeth upon this foundation iron, brass, or lead, that is, the greater sort of sins, and therefore more hard, and consequently not remissible in that place: but wood, hay, stubble, that is, little and very light sins, which the fire doth easily consume. Yet we have here further to consider, that none can be there purged, no, not for the least sins that be, unless in his lifetime he deserved by virtuous works to find such favour in that place.

~Pope St. Gregory I (c. 540-604): Dialogues, Book IV, Chap. 39.

Purgatory, by Jacopo (Comin) Tintoretto (1518–1594)