Markale, Jean. The Grail : The Celtic Origins of the Sacred Icon.

“The Celtic tales on which the Grail legend is based emphasize the theme of the Quest. Through his exploration of several versions of this myth that appeared in the Middle Ages, Jean Markale digs deep beneath the Christian veneer of these tales, allowing us to penetrate to the true meaning of the Grail and its Quest, legacies of a rich Celtic spirituality that has nourished the Western psyche for centuries. He also examines how these myths were later used by the Knights Templar, as well as how their links with Alchemy and Catharism played a decisive role in the shaping of Western Hermetic thought.”