Then anon they heard cracking and crying of thunder, that them thought the place should all to-drive. In the midst of this blast entered a sunbeam more clearer by seven times than ever they saw day, and all they were alighted of the grace of the Holy Ghost. Then began every knight to behold other, and either saw other, by their seeming, fairer than ever they saw afore. Notforthan there was no knight might speak one word a great while, and so they looked every man on other as they had been dumb.

Then there entered into the hall the Holy Grail covered with white samite, but there was none might see it, nor who bare it. And there was all the hall fulfilled with good odours, and every knight had such meats and drinks as he best loved in this world. And when the Holy Grail had been borne through the hall, then the Holy Vessel departed suddenly, that they wist not where it became; then had they all breath to speak.

And then the king yielded thankings to God, of His good grace that he had sent them. “Certes,” said the king, “we ought to thank Our Lord Jesu greatly for that he hath shewed us this day, at the reverence of this high feast of Pentecost.”

“Now,” said Sir Gawain, “we have been served this day of what meats and drinks we thought on; but one thing beguiled us, we might not see the Holy Grail, it was so preciously covered. Wherefore I will make here avow, that tomorn, without longer abiding, I shall labour in the quest of the Sangrail, that I shall hold me out a twelvemonth and a day, or more if need be, and never shall I return again unto the court till I have seen it more openly than it hath been seen here; and if I may not speed I shall return again as he that may not be against the will of Our Lord Jesu Christ.”

When they of the Table Round heard Sir Gawain say so, they arose up the most part and made such avows as Sir Gawain had made. Anon as King Arthur heard this he was greatly displeased, for he wist well they might not again-say their avows.

“Alas,” said King Arthur unto Sir Gawain, “ye have nigh slain me with the avow and promise that ye have made; for through you ye have bereft me the fairest fellowship and the truest of knighthood that ever were seen together in any realm of the world; for when they depart from hence I am sure they all shall never meet more in this world, for they shall die many in the quest. And so it forthinketh me a little, for I have loved them as well as my life, wherefore it shall grieve me right sore, the departition of this fellowship; for I have had an old custom to have them in my fellowship.”

– Thomas Malory, Le Morte D’Arthur, Book 13, Chapter 7

Read the other Great Myths here