If Kurt Vonnegut's Slaughterhouse-Five had come out a few years later, we might never have heard of it
The main theme of the book is about war and 'Billy Pigrims' experience of this. I think it goes much deeper than this looking at an alternative meaning to 'life and death'. Whether we do actually die or live our same life over several times. Or whether Billy was truly insane or in fact experiencing all his time traveling. But then again I do tend to read more into things.. sometimes!