Climb Ev'ry Mountain

 was a song that Fitz Kreiner once sung to Sasha while they were crossing the Pyrenees during the Spanish Civil War in 1937. He sang at least the following snippet of the song: Climb every mountain, ford every stream, some line I've forgot, till you find that dream He did so deliberately to test whether Sasha, a man purporting to be from 1937, would recognise the song, which came from a later period in time. Sasha appeared not to know the song, which Fitz then had to pass off as "something I wrote". (PROSE: History 101)

Behind the scenes
Technically, the song is not named in History 101, but enough of the lyrics are present to logically resolve its name.