you don;t have to take my word for it, listen to this guy --
http://www.youtube.com/watch?v=fW_Dv_GNQAo
"...First of all, the name 'moonlight' is nonsense ..."
from 8'50" onward:
"... It was crystal clear to me what this music was about, no moonlight, but it's a funeral scene, it's a death scene, thinking of Mozart's Don Giovanni ..."