LONDON.- It is the greatest romance of chivalry produced in the Middle Ages, and its themes of friendship, treachery, ambition, achievement and star-crossed tragic lovers form the foundations of much of our modern literature. The stories of the quest for the Holy Grail, of the Lady of the Lake, of King Arthur and his court at Camelot, and of Sir Lancelot and Queen Guinevere, captured the imaginations of generations to come, and have inspired some of the best-selling novels of our time. The Rochefoucauld Grail is from the 14th century, and on a scale which is as impressive as the text: some 200 cows would have been needed to produce the vellum sheets that make up the three monumental volumes, the whole embellished with some 107 jewel like illuminated illustrations – each one a work of art in its own right. Dr Timothy Bolton, specialist in charge of the sale at Sotheby’s, said: “This is one of the principal manus