There are, after all, different types of knowing. Science studies the repeatable; history studies the unrepeatable. Caesar only crossed the Rubicon once, and if he’d crossed it again it would have meant something different the second time. There was, and could be, only one first landing on the moon. The fall of the second Jerusalem Temple took place in a.d. 70 and never happened again. Historians don’t of course see this as a problem and are usually not shy about declaring that these events certainly took place, even though we can’t repeat them in the laboratory.
