Memento

As I was watching the movie, I couldn't help but feel sorry for Leonard and the lonely life he lives. It's pretty much like he's living in an tangible, Earth form of Limbo, can't go anywhere and can't remember anyone. First and foremost, he lost his wife, which would drive anyone crazy however what really drilled the nail into the coffin was that she died, in both sequences, a painful death; in Leonard's sequence she was brutally murdered before him, and in another she could not bear to endure her husband's loss of memory and virtually had him kill her. On top of all that, Leonard lost his job, his house, his money, his friends...the list goes on. What I have to ask is, what was his motivation to live? To realize that it was all for nothing? Perhaps this thought has crossed his mind once or twice before but alas he cannot remember.