If you've ever used the phrase "save the world" what exactly did you have in mind as the focal thing that needed "saving"?
Eg: environment, civilization, tradition, progress, oppressed people, etc. etc.
i think to me it's more or less about saving the current "snapshot" (think backup) so that i preserve the *feeling* i have about the world at the moment.
all to avoid the "yeah, cool, but that's not what i had in mind" kind of situations.