Is there a logic of history? Is there, beyond all the casual and incalculable elements of the separate events, something that we may call a metaphysical structure of historic humanity, something that is essentially independent of the outward forms – social, spiritual and political – which we see so clearly? (Oswald Spengler, Der Untergang des Abendlandes, 1918. English translation. The Decline of the West, 1926)