The literature surrounding the Grail can be divided into two groups. The first concerns King Arthur's knights visiting the Grail castle or questing after the object. The second concerns the Grail's earlier history in the time of Joseph of Arimathea.

The nine works from the first group are:
• Perceval, the Story of the Grail, a chivalric romance poem by Chrétien de Troyes.
• The Four Continuations of Chrétien's unfinished poem, by authors of differing vision, designed to bring the story to a close.
• The Didot Perceval [fr], purportedly a prosification of Robert de Boron's sequel to his romance poems Joseph d'Arimathie [fr] and Merlin.
• Parzival by Wolfram von Eschenbach, which adapted at least the holiness of Robert's Grail into the framework of Chrétien's story.
• Welsh romance Peredur son of Efrawg, a loose translation of Chrétien's poem and the Continuations, with some influence from native Welsh literature.
• Perlesvaus, called the "least canonical" Grail romance because of its very different character.
• German poem Diu Crône (The Crown), in which Gawain, rather than Perceval, achieves the Grail.
• The Prose Lancelot section of the vast Lancelot-Grail cycle introduced the new Grail hero, Galahad. The Queste del Saint Graal, a follow-up part of the cycle, concerns Galahad's eventual achievement of the Grail.
Of the second group there are:
• Robert de Boron's Joseph d'Arimathie.
• The Estoire del Saint Graal, the first part of the Lancelot-Grail cycle (but written after Lancelot and the Queste), based on Robert's tale but expanding it greatly with many new details.
• Verses by Rigaut de Barbezieux, a late 12th or early 13th-century Provençal troubador, where mention is made of Perceval, the lance, and the Grail served.
The Grail was considered a bowl or dish when first described by Chrétien de Troyes. There, it is a processional salver, a tray, used to serve at a feast. Hélinand of Froidmont described a grail as a "wide and deep saucer" (scutella lata et aliquantulum profunda); other authors had their own ideas. Robert de Boron portrayed it as the vessel of the Last Supper. Peredur son of Efrawg had no Grail as such, presenting the hero instead with a platter containing his kinsman's bloody, severed head.
The Grail is first featured in Perceval, le Conte du Graal (The Story of the Grail) by Chrétien de Troyes, who claims he was …

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In the wake of the Arthurian romances, several artifacts came to be identified as the Holy Grail in medieval relic veneration. These artifacts are said to have been the vessel used at the Last Supper, but other details vary. Despite the prominence of the Grail literature, traditions about a Last Supper relic remained rare in contrast to other items associated with Jesus' last days, such as the True Cross and Holy Lance.

One tradition predates the Grail romances: in the 7th century, the pilgrim Arculf reported that the Last Supper chalice was displayed near Jerusalem. In the wake of Robert de Boron's Grail works, several other items came to be claimed as the true Last Supper vessel. In the late 12th century, one was said to be in Byzantium; Albrecht von Scharfenberg's Grail romance Der Jüngere Titurel associated it explicitly with the Arthurian Grail, but claimed it was only a copy. This item was said to have been looted in the Fourth Crusade and brought to Troyes in France, but it was lost during the French Revolution.

Two relics associated with the Grail survive today. The Sacro Catino (Sacred Basin, also known as the Genoa Chalice) is a green glass dish held at the Genoa Cathedral said to have been used at the Last Supper. Its provenance is unknown, and there are two divergent accounts of how it was brought to Genoa by Crusaders in the 12th century. It was not associated with the Last Supper until later, in the wake of the Grail romances; the first known association is in Jacobus de Voragine's chronicle of Genoa in the late 13th century, which draws on the Grail literary tradition. The Catino was moved and broken during Napoleon's conquest in the early 19th century, revealing that it is glass rather than emerald.

The Holy Chalice of Valencia is an agate dish with a mounting for use as a chalice. The bowl may date to Greco-Roman times, but its dating is unclear, and its provenance is unknown before 1399, when it was gifted to Martin I of Aragon. By the 14th century, an elaborate tradition had developed that this object was the Last Supper chalice. This tradition mirrors aspects of the Grail material, with several major differences, suggesting a separate tradition entirely. It is not associated with Joseph of Arimathea or Jesus' blood; it is said to have been taken to Rome by Saint Peter and later entrusted to Saint Lawrence. Early references do not call the object the "Grail"; the first evidence connecting it to the Grail tradition is from the 15th century. The monarchy sold the cup in the 15th century to Valencia Cathedral, where it remains a significant local icon.

Several objects were identified with the Holy Grail in the 17th century. In the 20th century, a series of new items became associated with it. These include the Nanteos Cup, a medieva…

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Since the 19th century, the Holy Grail has been linked to various conspiracy theories. In 1818, Austrian pseudohistorical writer Joseph von Hammer-Purgstall connected the Grail to contemporary myths surrounding the Knights Templar that cast the order as a secret society dedicated to mystical knowledge and relics. In Hammer-Purgstall's work, the Grail is not a physical relic, but a symbol of the secret knowledge that the Templars sought. There is no historical evidence linking the Templars to a search for the Grail, but subsequent writers have elaborated on the Templar theories.

Starting in the early 20th century, writers, particularly in France, further connected the Templars and Grail to the Cathars. In 1906, French esoteric writer Joséphin Péladan identified the Cathar castle of Montségur with Munsalväsche or Montsalvat, the Grail castle in Wolfram's Parzival. This identification has inspired a wider legend asserting that the Cathars possessed the Holy Grail. According to these stories, the Cathars guarded the Grail at Montségur, and smuggled it out when the castle fell in 1244.

Beginning in 1933, German writer Otto Rahn published a series of books tying the Grail, Templars, and Cathars to modern German nationalist mythology. According to Rahn, the Grail was a symbol of a pure Germanic religion repressed by Christianity. Rahn's books inspired interest in the Grail within Nazi occultist circles, and led to the SS chief Heinrich Himmler's abortive sponsorship of Rahn's search for the Grail, as well as many subsequent conspiracy theories and fictional works about the Nazis searching for the Grail.

In the late 20th century, writers Michael Baigent, Richard Leigh, and Henry Lincoln created one of the most widely known conspiracy theories about the Holy Grail. The theory first appeared on the BBC documentary series Chronicle in the 1970s, and was elaborated upon in the bestselling 1982 book Holy Blood, Holy Grail. The theory combines myths about the Templars and Cathars with various other legends, and a prominent hoax about a secret order called the Priory of Sion. According to this theory, the Holy Grail is not a physical object, but a symbol of the bloodline of Jesus. The blood connection is based on the etymological reading of san greal (holy grail) as sang real (royal blood), which dates to the 15th century. The narrative developed is that Jesus was not divine, and had children with Mary Magdalene, who took the family to France where their descendants became the Merovingian dynasty. Supposedly, while the Catholic Church worked to destroy the dynasty, they were protected by the Priory of Sion and their associates, including the Templars, Cathars, and other secret societies. The book, its arguments, and its evidence have be…

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