I just realized the Reformation is a pretty good example of something similar... though more along the rhymes than repeats line (Mark Twain), as another person pointed out. Look at the impact that had, and the 500 years since then.  By the time the dust settles (and I don't think we've seen anything yet, in terms of what is coming), the events of our lifetimes will easily impact the next 500 years. IMHO.