"What Is So Rare As A Day In June?"
Context: The Holy Grail, the cup out of which Jesus partook of the Last Supper, was by tradition carried to England by Joseph of Arimathea and there guarded by his descendants who were required to be chaste in thought, word, and deed. When one of them broke his vow, the cup disappeared. The Knights of King Arthur and, in Lowell's poem, even others who lived after them, devoted their lives to a search for it. Lowell invents the story of a knight, Sir Launfal, who after roaming the world to seek it, finds it in his own castle, the cup that the knight had humbly filled to quench the thirst of a leper. The poet starts with a prelude comparing his own efforts to the search by a musing organist for his theme. "Rare" has the meaning, not of uncommon, but of precious or delightful. Lowell describes the coming of Spring, the time when Sir Launfal remembers his pledge to go seeking the Grail.
And what is so rare as a day in June?Then, if ever, come perfect days;Then Heaven tries earth if it be in tune,And over it softly her warm ear lays;Whether we look, or whether we listen,We hear life murmur, or see it glisten.