Crétien de Troyes' Perceval

In the romance 'Perceval. The Story of the
Grail', written by French poet Chretien de
Troyes in the late 12 century, the titular knight
ends up at the court of the mysterious Fisher
King, where he is presented with a golden
grail, supposedly the vessel in which Joseph
of Arimathea collected Jesus' blood.
"How wretched is the man who sees the perfect
opportunity and still waits for a better one."