Medieval Arthurian legend
Of Arthour and of Merlin
14th century Middle English. National Library of Scotland MS Advocates 19.2.1, the Auchinleck Manuscript; Lincoln's Inn Library, Hale MS 150.
'I’ve no idea who any of those three were,' said Gawain.
'All three were one. It was Merlin,' said Earl Do.
This Romance says that Gawain asked Yvain about the letters which Yvain had sent requesting assistance, and Yvain said that he hadn’t sent any letters, which puzzled them both. …
When [Gawain and Yvain and their young companions] arrived in London they were made suitably welcome. Earl Do gave the high palace to Gawain the courteous, to use as his own. Gawain installed his mother there and swore by Mary the queen of heaven that until he’d persuaded his father to seek reconciliation with King Arthur, his father wouldn’t learn where she was. Then he told Earl Do all about his recent encounters with the heathen army: how he had been able to rescue Segremour because an old man had brought news of him, and then saved Yvain from certain death through letters in Latin that Yvain had never written, delivered by a boy he didn’t know, ‘and then I saved my mother’s life,’ he said, ‘through the guidance of an unknown knight. I’ve no idea who any of those three were, and all three of them just vanished afterwards.’
‘Oh Gawain,’ said Do. ‘All three were one. It was Merlin. One day you’ll be friends with this good fellow.’ They marvelled at this and made a good joke of it.