Book XI - Chapter VIII - How Dame Brisen by enchantment brought Sir Launcelot to Dame Elaine's bed, and how Queen Guenever rebuked him.
SO when time came that all folks were abed, Dame Brisen came to Sir Launcelot's bed's side and said: Sir Launcelot du Lake, sleep you? My lady, Queen Guenever, lieth and awaiteth upon you. O my fair lady, said Sir Launcelot, I am ready to go with you where ye will have me. So Sir Launcelot threw upon him a long gown, and his sword in his hand; and then Dame Brisen took him by the finger and led him to her lady's bed, Dame Elaine; and then she departed and left them in bed together. Wit you well the lady was glad, and so was Sir Launcelot, for he weened that he had had another in his arms.
Now leave we them kissing and clipping, as was kindly thing; and now speak we of Queen Guenever that sent one of her women unto Sir Launcelot's bed; and when she came there she found the bed cold, and he was away; so she came to the queen and told her all. Alas, said the queen, where is that false knight become? Then the queen was nigh out of her wit, and then she writhed and weltered as a mad woman, and might not sleep a four or five hours. Then Sir Launcelot had a condition that he used of custom, he would clatter in his sleep, and speak oft of his lady, Queen Guenever. So as Sir Launcelot had waked as long as it had pleased him, then by course of kind he slept, and Dame Elaine both. And in his sleep he talked and clattered as a jay, of the love that had been betwixt Queen Guenever and him. And so as he talked so loud the queen heard him thereas she lay in her chamber; and when she heard him so clatter she was nigh wood and out of her mind, and for anger and pain wist not what to do. And then she coughed so loud that Sir Launcelot awaked, and he knew her hemming. And then he knew well that he lay not by the queen; and therewith he leapt out of his bed as he had been a wood man, in his shirt, and the queen met him in the floor; and thus she said: False traitor knight that thou art, look thou never abide in my court, and avoid my chamber, and not so hardy, thou false traitor knight that thou art, that ever thou come in my sight. Alas, said Sir Launcelot; and therewith he took such an heartly sorrow at her words that he fell down to the floor in a swoon. And therewithal Queen Guenever departed. And when Sir Launcelot awoke of his swoon, he leapt out at a bay window into a garden, and there with thorns he was all to-scratched in his visage and his body; and so he ran forth he wist not whither, and was wild wood as ever was man; and so he ran two year, and never man might have grace to know him.