High Quality Content by WIKIPEDIA articles! Oswald Arnold Gottfried Spengler (29 May 1880, Blankenburg am Harz, then Duchy of Brunswick, German Empire 8 May 1936, Munich, Germany) was a German historian and philosopher whose interests also included mathematics, science, and art. He is best known for his book The Decline of the West (Der Untergang des Abendlandes), which puts forth a cyclical theory of the rise and decline of civilizations. After Decline was published in 1918, Spengler produced ...