Purgatory ~ depth of God's mercy

Based on Catholic doctrine and teaching 'Purgatory' is a period of purification after death.

Each man receives his eternal retribution in his immortal soul at the very moment of his death, in a particular judgement that refers his life to Christ: either entrance into the blessedness of heaven — through a purification or immediately, — or immediate and everlasting damnation. (CCC, 1022)

It is not exactly a second chance given for those who have not won the reward of kingdom of God (heaven). It is a transitional state for those who have merited heaven but still have aspects of their souls that still require purification. It reveals the depth of God's mercy whereby even those who are not yet perfect can attain the fullness of heaven.

All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven. (CCC, 1030)

Eternal rest grant unto them, O Lord; 

And let perpetual light shine upon them. 

May they rest in peace. Amen.

Prayer of St. Gertrude the Great

Eternal Father, I offer Thee 

the most Precious Blood of Jesus, 

with all the Masses 

being said all over the world this day, 

for the Souls in Purgatory.

Our Lord showed St. Gertrude a vast number of souls leaving Purgatory and going to Heaven as a result of this prayer, which the Saint was accustomed to say frequently during the day.