The name of a legendary sacred vessel, variously identified with the chalice of the Eucharist or the dish of the Pascal lamb, and the theme of a famous medieval cycle of romance. In the romances the conception of the Grail varies considerably; its nature is often but vaguely indicated, and, in the case of Chrestien's Perceval poem, it is left wholly unexplained.
The meaning of the word has also been variously explained. The generally accepted meaning is that is given by the Cistercian chronicler Helinandus (d. about 1230), who, under the date of about 717, mentions of a vision, shown to a hermit concerning the dish used by Our Lord at the Last Supper, and about which the hermit then wrote a Latin book called "Gradale." "Now in French," so Helinandus informs us, "Gradalis or Gradale means a dish (scutella), wide and somewhat deep, in which costly viands are wont to be served to the rich in degrees (gradatim), one morsel after another in different rows. In popular speech it is also called "greal" because it is pleasant (grata) and acceptable to him eating therein" etc. The medieval Latin word "gradale" because in Old French "graal," or "greal," or "greel," whence the English "grail." Others derive the word from "garalis" or from "cratalis" (crater, a mixing bowl). It certainly means a dish, the derivation from "grata" in the latter part of the passage cited above or from "agréer" (to please) in the French romances is secondary. The explanation of "San greal" as "sang real" (kingly blood) was not current until the later Middle Ages. Other etymologies that have been advanced may be passed over as obsolete. When we come to examine the literary tradition concerning the Grail we notice at the outset that the Grail legend is closely connected with that of Perceval as well as that of King Arthur. Yet all these legends were originally independent of each other. The Perceval story may have a mythical origin, or it may be regarded as the tale of a simpleton (Fr., nicelot) who, however, in the end achieves great things. In all the versions that we have of it, it is a part of of the Arthurian legend, and, in almost all, it is furthermore connected with the Grail. So the reconstruction of the original Grail legend can be accomplished only by an analytical comparison of all extant versions, and is a task that has given rise to some of the most difficult problems in the whole range of literary history.
The early history of the Grail is intimately connected with the story of Joseph of Arimathea. When he is cast into prison by the Jews, Christ appears to him and gives him the vessel, through which he is miraculously sustained for forty-two years, until liberated by Vespasian. The Grail is then brought to the West, to Britain, either by Joseph and Josephes, his son (Grand St. Graal), or by Alain one of his kin (Robert de Boron). Galaad (or Perceval) achieves the quest; after the death of its keeper the Grail vanishes. According to the version of the "Perlesvaus" Perceval is removed, no one knows whither, by a ship with white sails on which is displayed a red cross. In the Guiot-Wolfram version we meet with a conception of the Grail wholly different from that of the French romances. Wolfram conceives of it as a precious stone, lapsit exillis (i.e. lapis or lapsi ex caelis?) of special purity, possessing miraculous powers conferred upon it and sustained by a consecrated Host which, on every Good Friday, a dove brings down from heaven and lays down upon it. The angels who remained neutral during the rebellion of Lucifer were its first guardians; then it was brought to earth and entrusted to Titurel, the first Grail king. It is guarded in the splendid castle of Munsalvaesche (mons salvationis or silvaticus?) by itself and nourished by its miraculous food-giving power.