“I saw a great multitude which no man could number…These are they who have come out of the great tribulation and have washed their robes and made them white in the Blood of the Lamb. Therefore they are before the throne of God, and serve Him day and night in His temple, and He who sits upon the throne will dwell with them.” (Rev. 7:9)
“All the elect who have palms in the hands, and who are wholly bathed in the great light of God, have had first to pass through the ‘great tribulation,’ to know this sorrow ‘immense as the sea,’ of which the psalmist sang. Before contemplating with uncovered face the glory of the Lord,’ they have shared in the annihilation of His Christ: before being ‘transformed from brightness to brightness in the image of the Divine Being,’ they have been conformed in the image of the Word Incarnate, the One crucified by love.” –St. Elizabeth of the Trinity
Illumina Domine Blog - Devotion to The Holy Face 