`But do not you know the word, Gandalf?' asked Boromir in surprise.

`No!' said the wizard.

The others looked dismayed; only Aragorn, who knew Gandalf well, remained silent and unmoved.

`Then what was the use of bringing us to this accursed spot?' cried Boromir, glancing back with a shudder at the dark water. `You told us that you had once passed through the Mines. How could that be, if you did not know how to enter.

`The answer to your fist question, Boromir,' said the wizard, `is that I do not know the word - yet. But we shall soon see. And,' he added with a glint in his eyes under their bristling brows, `you may ask what is the use of my deeds when they are proved useless. As for your other question: do you doubt my tale? Or have you no wits left? I did not enter this way. I came from the East.'

from The Fellowship of the Ring "A Journey in the Dark".