“Durin, Durin!” said Thorin. “He was the father of the fathers of the eldest race of Dwarves, the Longbeards, and my first ancestor: I am his heir.” “Then what is Durin’s Day?” asked Elrond. “The first day of the dwarves’ New Year,” said Thorin, “is as all should know the first day of the last moon of Autumn on the threshold of Winter. We still call it Durin’s Day when the last moon of Autumn and the sun are in the sky together. But this will not help us much, I fear, for it passes our skill in these days to guess when such a time will come again.”
