Exclusivity of the Grail

This grail of which I have read about in The Quest for the Holy Grail seems to be a much more exclusive object than the cauldron formerly owned by my dearly departed brother, Bendigeid Vran. Although this heavenly object supplies food in abundance to those who behold it, it is only the pure of heart and the humble who are allowed to approach it. Indeed, it seems that this grail can only be used for good by the good. The cauldron, on the other hand, seems to have served whoever possessed it; it was used by the armies of my husband Matholwch and his people to subdue the armies of my brother. Verily, the cauldron did not seem to be exclusively for use for good or evil—it was simply magical. If only the cauldron had been as exclusive as the grail! Perhaps, then, the Irish soldiers would not have been restored by the cauldron’s magical properties, and the people of my brother’s house would have prevailed without his being mortally wounded.
Despite my appreciation for the exclusivity of this grail, I cannot help but pity poor Lancelot. As one who has both received and caused a great deal of suffering, I understand the anguish Sir Lancelot must experience at his inability to approach this most holy object.