I THOUGHT I was not alone, walking here by the shore, 
   But the one I thought was with me, as now I walk by the shore, 
   As I lean and look through the glimmering light--that one has utterly 
         disappeared, 
   And those appear that perplex me.
Walt Whitman
http://www.poemhunter.com/poem/i-thought-i-was-not-alone/