Commentary Par XX 127-129

The three ladies are obviously the three theological virtues, whom we saw at the right wheel of the chariot of the Church Triumphant in [Purg XXIX 121-129].  In what sense did they 'serve to baptize' Ripheus?  Since that ritual was not available to him, and since he was born with original sin upon him, he required something in its place.  Somehow he acquired the three theological virtues and these brought him to Christ.  Dante's text here may reflect a passage in St. Augustine's De doctrina christiana I.xxxix.43: 'Thus a man supported by faith, hope, and charity, with an unshaken hold upon them, does not need the Scriptures except for the instruction of others' (tr. D.W. Robertson, Jr.).

The date of the fall of Troy was given in at least one universal history (that of Petavius) as 1184 B.C.; citation of Petavius may be found in a number of commentaries, beginning with Lombardi (DDP Lombardi.Par.XX.127-129).