So when they were served, and all the sieges fulfilled save only the Siege Perilous, anon there befell a marvellous adventure, that all the doors and the windows of the palace shut by themselves, but for all that the hall was not greatly darked, and therewith they were all abashed both one and other. Then King Arthur spake first, and said, "Fair fellows and lords, we have seen this day marvels, but or night I suppose we shall see greater marvels."
In the meanwhile came in a good old man and an ancient, clothed all in white; and there was no knight that knew from whence he came. And with him he brought a young knight, both on foot, in red arms, without sword or shield, save a scabbard hanging by his side; and these words he said, "Peace be with you, fair lords." Then the old man said unto King Arthur, "Sir, I bring you here a young knight that is of king's lineage, and of the kindred of Joseph of Arimathea, whereby the marvels of this court and of strange realms shall be fully accomplished."
The king was right glad of his words, and said unto the good man, "Sir, ye be right heartily welcome, and the young knight with you."
Then the old man made the young knight to unarm him; and he was in a coat of red sendall, and bare a mantle upon his shoulder that was furred with fine ermines, and put that upon him. And the old man said unto the young knight, "Sir, follow after."
And anon he led him unto the Siege Perilous, where beside sat Sir Launcelot; and the good man lifted up the cloth, and found there letters that said thus: "This is the siege of Galahad the haut [high] prince."
Then all the knights of the Table Round marvelled them greatly of Sir Galahad, that he durst sit there in that Siege Perilous, and was so tender of age, and wist not from whence he came, but all only by God, and said, This is he by whom the Sancgreal shall be achieved, for there sat never none but he, but he were mischieved. Then Sir Launcelot beheld his son, and had great joy of him.
Then came King Arthur unto Sir Galahad, and said, "Sir, ye be welcome, for ye shall move many good knights unto the quest of the Sancgreal, and ye shall achieve that never knight might bring to an end."
Then the king took him by the hand, and went down from the palace to show Sir Galahad the adventure of the stone.
The queen heard thereof, and came after with many ladies, and showed them the stone where it hoved on the water. "Sir," said the king unto Sir Galahad, "here is a great marvel as ever I saw, and right good knights have assayed and failed."
"Sir," said Galahad, "that is no marvel, for this adventure is not theirs, but mine, and for the surety of this sword I brought none with me; for here by my side hangeth the scabbard."