In my view I see rebirth as factual natural process. Most of the confusion I think lies in the term rebirth itself. No one is actually reborn, so.... Yeah, I couldn't agree more that speculation on past and future are a waste of time. This is also why I see rebirth, for lack of a better term, as wonderful motivation to practice well in the present. Then again I may be one of the few who believe nibbana can be realized in this lifetime. I'm just enjoying samsara for now. Thanks for your above post. It does make a lot of sense to me, even if I don't quite see it the same way.