Many times had the Feast of Pentecost come round, and many were the knights that Arthur had made after he founded the Order of the Round Table; yet no knight had appeared who dared claim the seat named by Merlin the Siege Perilous. At last, one vigil of the great feast, a lady came to Arthur's court at Camelot and asked Sir Launcelot to ride with her into the forest hard by, for a purpose not then to be revealed. Launcelot consenting, they rode together until they came to a nunnery hidden deep in the forest; and there the lady bade Launcelot dismount, and led him into a great and stately room. Presently there entered twelve nuns and with them a youth, the fairest that Launcelot had ever seen. "Sir," said the nuns, "we have brought up this child in our midst, and now that he is grown to manhood, we pray you make him knight, for of none worthier could he receive the honour." "Is this thy own desire?" asked Launcelot of the young squire; and when he said that so it was, Launcelot promised to make him knight after the great festival had been celebrated in the church next day.

So on the morrow, after they had worshipped, Launcelot knighted Galahad—for that was the youth's name—and asked him if he would ride at once with him to the King's court; but the young knight excusing himself, Sir Launcelot rode back alone to Camelot, where all rejoiced that he was returned in time to keep the feast with the whole Order of the Round Table.

Now, according to his custom, King Arthur was waiting for some marvel to befall before he and his knights sat down to the banquet. Presently a squire entered the hall and said: "Sir King, a great wonder has appeared. There floats on the river a mighty stone, as it were a block of red marble, and it is thrust through by a sword, the hilt of which is set thick with precious stones." On hearing this, the King and all his knights went forth to view the stone and found it as the squire had said; moreover, looking closer, they read these words: "None shall draw me hence, but only he by whose side I must hang; and he shall be the best knight in all the world." Immediately, all bade Launcelot draw forth the sword, but he refused, saying that the sword was not for him. Then, at the King's command, Sir Gawain made the attempt and failed, as did Sir Percivale after him. So the knights knew the adventure was not for them, and returning to the hall, took their places about the Round Table.

No sooner were they seated than an aged man, clothed all in white, entered the hall, followed by a young knight in red armour, by whose side hung an empty scabbard. The old man approached King Arthur and bowing low before him, said: "Sir, I bring you a young knight of the house and lineage of Joseph of Arimathea, and through him shall great glory be won for all the land of Britain." Greatly did King Arthur rejoice to hear this, and welcomed the two right royally. Then when the young knight had saluted the King, the old man led him to the Siege Perilous and drew off its silken cover; and all the knights were amazed, for they saw that where had been engraved the words, "The Siege Perilous," was written now in shining gold: "This is the Siege of the noble prince, Sir Galahad." Straightway the young man seated himself there where none other had ever sat without danger to his life; and all who saw it said, one to another: "Surely this is he that shall achieve the Holy Grail." Now the Holy Grail was the blessed dish from which our Lord had eaten the Last Supper, and it had been brought to the land of Britain by Joseph of Arimathea; but because of men's sinfulness, it had been withdrawn from human sight, only that, from time to to time, it appeared to the pure in heart.

When all had partaken of the royal banquet, King Arthur bade Sir Galahad come with him to the river's brink; and showing him the floating stone with the sword thrust through it, told him how his knights had failed to draw forth the sword. "Sir," said Galahad, "it is no marvel that they failed, for the adventure was meant for me, as my empty scabbard shows." So saying, lightly he drew the sword from the heart of the stone, and lightly he slid it into the scabbard at his side. While all yet wondered at this adventure of the sword, there came riding to them a lady on a white palfrey who, saluting King Arthur, said: "Sir King, Nacien the hermit sends thee word that this day shall great honour be shown to thee and all thine house; for the Holy Grail shall appear in thy hall, and thou and all thy fellowship shall be fed therefrom." And so to Launcelot she said: "Sir Knight, thou hast ever been the best knight of all the world; but another has come to whom thou must yield precedence." Then Launcelot answered humbly: "I know well I was never the best." "Ay, of a truth thou wast and art still, of sinful men," said she, and rode away before any could question her further.

So, that evening, when all were gathered about the Round Table, each knight in his own siege, suddenly there was heard a crash of thunder, so mighty that the hall trembled, and there flashed into the hall a sunbeam, brighter far than any that had ever before been seen; and then, draped all in white samite, there glided through the air what none might see, yet what all knew to be the Holy Grail. And all the air was filled with sweet odours, and on every one was shed a light in which he looked fairer and nobler than ever before. So they sat in an amazed silence, till presently King Arthur rose and gave thanks to God for the grace given to him and to his court. Then up sprang Sir Gawain and made his avow to follow for a year and a day the Quest of the Holy Grail, if perchance he might be granted the vision of it. Immediately other of the knights followed his example, binding themselves to the Quest of the Holy Grail until, in all, one hundred and fifty had vowed themselves to the adventure.

Then was King Arthur grieved, for he foresaw the ruin of his noble Order. And turning to Sir Gawain, he said: "Nephew, ye have done ill, for through you I am bereft of the noblest company of knights that ever brought honour to any realm in Christendom. Well I know that never again shall all of you gather in this hall, and it grieves me to lose men I have loved as my life and through whom I have won peace and righteousness for all my realm." So the King mourned and his knights with him, but their oaths they could not recall.

Great woe was there in Camelot next day when, after worship in the cathedral, the knights who had vowed themselves to the Quest of the Holy Grail got to horse and rode away. A goodly company it was that passed through the streets, the townfolk weeping to see them go; Sir Launcelot du Lac and his kin, Sir Galahad of whom all expected great deeds, Sir Bors and Sir Percivale, and many another scarcely less famed than they. So they rode together that day to the Castle of Vagon, where they were entertained right hospitably, and the next day they separated, each to ride his own way and see what adventures should befall him.

So it came to pass that, after four days' ride, Sir Galahad reached an abbey. Now Sir Galahad was still clothed in red armour as when he came to the King's court, and by his side hung the wondrous sword; but he was without a shield. They of the abbey received him right heartily, as also did the brave King Bagdemagus, Knight of the Round Table, who was resting there. When they greeted each other, Sir Galahad asked King Bagdemagus what adventure had brought him there. "Sir," said Bagdemagus, "I was told that in this abbey was preserved a wondrous shield which none but the best knight in the world might bear without grievous harm to himself. And though I know well that there are better knights than I, to-morrow I purpose to make the attempt. But, I pray you, bide at this monastery a while until you hear from me; and if I fail, do ye take the adventure upon you." "So be it," said Sir Galahad.

The next day, at their request, Sir Galahad and King Bagdemagus were led into the church by a monk and shown where, behind the altar, hung the wondrous shield, whiter than snow save for the blood-red cross in its midst. Then the monk warned them of the danger to any who, being unworthy, should dare to bear the shield. But King Bagdemagus made answer: "I know well that I am not the best knight in the world, yet will I try if I may bear it." So he hung it about his neck, and, bidding farewell, rode away with his squire.

The two had not journeyed far before they saw a knight approach, armed all in white mail and mounted upon a white horse. Immediately he laid his spear in rest and, charging King Bagdemagus, pierced him through the shoulder and bore him from his horse; and standing over the wounded knight, he said: "Knight, thou hast shown great folly, for none shall bear this shield save the peerless knight, Sir Galahad." Then, taking the shield, he gave it to the squire and said: "Bear this shield to the good Knight Galahad and greet him well from me." "What is your name?" asked the squire. "That is not for thee or any other to know." "One thing, I pray you," said the squire; "why may this shield be borne by none but Sir Galahad without danger?" "Because it belongs to him only," answered the stranger knight, and vanished.

Then the squire took the shield and setting King Bagdemagus on his horse, bore him back to the abbey where he lay long, sick unto death. To Galahad the squire gave the shield and told him all that had befallen. So Galahad hung the shield about his neck and rode the way that Bagdemagus had gone the day before; and presently he met the White Knight, whom he greeted courteously, begging that he would make known to him the marvels of the red-cross shield. "That will I gladly," answered the White Knight. "Ye must know, Sir Knight, that this shield was made and given by Joseph of Arimathea to the good King Evelake of Sarras, that, in the might of the holy symbol, he should overthrow the heathen who threatened his kingdom. But afterwards, King Evelake followed Joseph to this land of Britain where they taught the true faith unto the people who before were heathen. Then when Joseph lay dying, he bade King Evelake set the shield in the monastery where ye lay last night, and foretold that none should wear it without loss until that day when it should be taken by the knight, ninth and last in descent from him, who should come to that place the fifteenth day after receiving the degree of knighthood. Even so has it been with you, Sir Knight." So saying, the unknown knight disappeared and Sir Galahad rode on his way.

After Sir Launcelot had parted from his fellows at the Castle of Vagon, he rode many days through the forest without adventure, till he chanced upon a knight close by a little hermitage in the wood. Immediately, as was the wont of errant knights, they prepared to joust, and Launcelot, whom none before had overthrown, was borne down, man and horse, by the stranger knight. Thereupon a nun, who dwelt in the hermitage, cried: "God be with thee, best knight in all this world," for she knew the victor for Sir Galahad. But Galahad, not wishing to be known, rode swiftly away; and presently Sir Launcelot got to horse again and rode slowly on his way, shamed and doubting sorely in his heart whether this quest were meant for him.

Afterward Sir Galahad rescued Sir Percivale from twenty knights who beset him, and rode on his way till night-fall, when he sought shelter at a little hermitage. Thither there came in the night a damsel who desired to speak with Sir Galahad; so he arose and went to her. "Galahad," said she, "arm you and mount your horse and follow me, for I am come to guide you in your quest." So they rode together until they had come to the seashore and there the damsel showed Galahad a great ship into which he must enter. Then she bade him farewell, and he, going on to the ship, found there already the good knights Sir Bors and Sir Percivale, who made much joy of the meeting. They abode in that ship until they had come to the castle of King Pelles, who welcomed them right gladly. Then, as they all sat at supper that night, suddenly the hall was filled with a great light, and the holy vessel appeared in their midst, covered all in white samite. While they all rejoiced, there came a voice, saying: "My Knights whom I have chosen, ye have seen the holy vessel dimly. Continue your journey to the city of Sarras and there the perfect vision shall be yours."

Now in the city of Sarras had dwelt a long time Joseph of Arimathea, teaching its people the true faith, before ever he came into the land of Britain; but when Sir Galahad and his fellows came there after long voyage, they found it ruled by a heathen King named Estorause, who cast them into a deep dungeon. There they were kept a year, but at the end of that time, the tyrant died. Then the great men of the land gathered together to consider who should be their King; and, while they were in council, came a voice bidding them take as their King the youngest of the three knights whom Estorause had thrown into prison. So in fear and wonder they hastened to the prison, and, releasing the three knights, made Galahad King as the voice had bidden them.

Thus Sir Galahad became King of the famous city of Sarras, in far Babylon. He had reigned a year when, one morning early, he and the other two knights, his fellows, went into the chapel, and there they saw, kneeling in prayer, an aged man, robed as a bishop, and round him hovered many angels. The knights fell on their knees in awe and reverence, whereupon he that seemed a bishop turned to them and said: "I am Joseph of Arimathea, and I am come to show you the perfect vision of the Holy Grail." On the instant there appeared before them, without veil or cover, the holy vessel, in a radiance of light such as almost blinded them. Sir Bors and Sir Percivale, when at length they were recovered from the brightness of that glory, looked up to find that the holy Joseph and the wondrous vessel had passed from their sight. Then they went to Sir Galahad where he still knelt as in prayer, and behold, he was dead; for it had been with him even as he had prayed; in the moment when he had seen the vision, his soul had gone back to God.

So the two knights buried him in that far city, themselves mourning and all the people with them. And immediately after, Sir Percivale put off his arms and took the habit of a monk, living a devout and holy life until, a year and two months later, he also died and was buried near Sir Galahad. Then Sir Bors armed him, and bidding farewell to the city, sailed away until, after many weeks, he came again to the land of Britain. There he took horse, and stayed not till he had come to Camelot. Great was the rejoicing of Arthur and all his knights when Sir Bors was once more among them. When he had told all the adventures which had befallen him and the good knights, his companions, all who heard were filled with amaze. But the King he caused the wisest clerks in the land to write in great books of the Holy Grail, that the fame of it should endure unto all time.