Spengler, Oswald (1880–1936), a German philosopher and historian. His The Decline of the West (1918–22) is a broad, sweeping interpretation of the rise and decline of cultures. He attempted to combine the knowledge of many fields—mathematics, natural sciences, the arts, and history—into a systematic philosophy of history. His main thesis was that history moves in cycles and that each great historic culture is subject to the same cycle of growth and decay. According to his analysis, the West had entered its declining phase and a new, more vigorous culture would rise.

Spengler's impact on the general public was widespread. His analysis suited the pessimistic mood that prevailed after World War I, and he became one of the most widely read authors of the 1920's. His influence in his native Germany was particularly farreaching. Many historians, however, disagreed with his central theme, which dismissed the idea of progress in history, and criticized him for inaccuracies and questionable methods.

Spengler was born in Blankenburg, Germany. He studied natural sciences and mathematics at the universities of Munich, Berlin, and Halle. After receiving his doctorate in 1904, Spengler became a schoolmaster. In 1911 he abandoned teaching to devote his time to further study and to writing.