The Historian’s function is to discern… alternatives …If we are to study history as a living subject, not merely as a coloured pageant, or an antiquarian chronicle, or a dogmatic scheme, we must not indeed lose ourselves in barren speculations, but we must leave some room for imagination. History is not merely what happened. It is what happened in the context of what might have happened. Therefore it must incorporate, as a necessary element, the alternatives, the might-have-beens.
— Hugh Trevor Roper