Does he mean a dialog like St Nicholas Tavelich had?
On November 11, 1391, he entered the Turkish mosque and with the zeal of a Saint Paul preached to a vast assembly there. He pleaded with tact and eloquence that Christ and His religion be accepted by the Turks in their hearts and homes. Before he had finished, he was apprehended and taken to the magistrates.
Questioned as to his faith, Nicholas joyfully professed his belief in the one true Church of Christ, defending it against every objection. This incensed the court to such an extent that he was knocked to the ground and attacked with great fury. Beaten almost to death, he was dragged into a dungeon, chained hand and foot, and kept for three days without food or drink.
On the fourth day he was taken out into the street, where he died the glorious death of a martyr, slashed to pieces with scimitars. God glorified His martyr by miracles, and Pope Leo XIII solemnly confirmed the veneration paid to him from time immemorial.
So, if I have this right, and can take this story to the bank, the dialog ended almost exactly, 2015 minus 1391 equals, six hundred twenty four years ago.