Acquainted with the Night
From Tardis Wiki, the free Doctor Who reference
"Acquainted with the Night" was a poem recited by Esther Drummond to Gwen Cooper. Its verses included:
I have been one acquainted with the night. I have walked out in rain and back in rain.
Esther noted that the poem was most likely not about walking, but about death. (TV: Dead of Night)
Behind the scenes
In the real world, "Acquainted with the Night" was written by Robert Frost.