high the door and three may walk abreast.’ “ “What are moon-letters?”
asked the hobbit full of excitement. He loved maps, as I have told you
before; and he also liked runes and letters and cunning handwriting,
though when he wrote himself it was a bit thin and spidery.
     “Moon-letters are rune-letters, but you cannot see them,” said Elrond,
“not when you look straight at them. They can only be seen when the
moon shines behind them, and what is more, with the more cunning sort
it must be a moon of the same shape and season as the day when they
were written. The dwarves invented them and wrote them with silver
pens, as your friends could tell you. These must have been written on
a midsummer’s eve in a crescent moon, a long while ago.”
     “What do they say?” asked Gandalf and Thorin together, a bit vexed
perhaps that even Elrond should have found this out first, though
really there had not been a chance before, and there would not have
been another until goodness knows when.
     “Stand by the grey stone when the thrush knocks,” read Elrond, “and
the setting sun with the last light of Durin’s Day will shine upon the
key-hole.” “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.