This is What You Call an "Essential Question"

Charlie Stross:

Assume you are a historian in the 30th century, compiling a pop history text about the period 1700-2300AD. What are the five most influential factors in that period of history?

Please note that this is a 600 year span—around the duration of the entire mediaeval period. Events a mere 20 years apart, such as the first and second world wars, merge together when viewed through the wrong end of a temporal telescope, just like the 30 years' war or the Wars of the Roses. Individual people, even hugely influential thinkers and rulers and tyrants, are a jumbled mass of names with dates attached. This is a question about the big issues—the ones big enough to remember half a millennium hence, like the Black Death, the Crusades, or the conquest of the Americas.