Lyric discussion by WeezDay 

Cover art for Little Ghost lyrics by White Stripes, The

this song is about a guy being so lonely that his mind creates the apparition of a beautiful young girl that he falls in love with. Hes not sure if she exists or not, but he is for sure that he's the only one who can see her (said several times)

There is a line that says "because of my condition". I interpreted the condition as insanity, meaning the ghost is entirely made up, and the guy is going crazy from lonliness