Now after I had passed by the wild beast, and had moved forward about thirty feet, lo! A virgin meets me, adorned as if she were proceeding from the bridal chamber, clothed entirely in white, and with white sandals, and veiled up to her forehead, and her head was covered by a hood. And she had white hair. I knew from my former visions that this was the Church, and I became more joyful. She saluted me, and said, “Hail, O man!” And I returned her salutation, and said, “Lady, hail!”
And she answered, and said to me, “Has nothing crossed your path?” I say, “I was met by a beast of such a size that it could destroy peoples, but through the power of the Lord and His great mercy I escaped from it.” “Well did you escape from it,” says she, “because you cast your care on God, and opened your heart to the Lord, believing that you can be saved by no other than by His great and glorious name. On this account the Lord has sent His angel, who has rule over the beasts, and whose name is Thegri, and has shut up its mouth, so that it cannot tear you.
You have escaped from great tribulation on account of your faith, and because you did not doubt in the presence of such a beast. Go, therefore, and tell the elect of the Lord His mighty deeds, and say to them that this beast is a type of the great tribulation that is coming. If then you prepare yourselves, and repent with all your heart, and turn to the Lord, it will be possible for you to escape it, if your heart be pure and spotless, and you spend the rest of the days of your life in serving the Lord blamelessly.
Cast your cares upon the Lord, and He will direct them. Trust the Lord, you who doubt, for He is all-powerful, and can turn His anger away from you, and send scourges on the doubters. Woe to those who hear these words, and despise them: better were it for them not to have been born.”
Source: The Pastor (or "The Shepherd") (New Advent)