The Era of High Modernity, while it really only lasted one lifespan (from 1875 to 1965), was uniquely notable as the period when virtually all of the most powerful people in the world (middle class, well educated urban dwellers of the biggest civilizations) held a decidedly dire Manichean take on Reality.
One of Modernity's leading lights, Baron Howard Florey, was fully typical in frankly preferring things to always be 'clearcut'.