After a stint volunteering in the medical service during World War I, Weber published three more books on religion in a sociological context. These works, The Religion of China (1916), The Religion of India (1916) and Ancient Judaism (1917-1918), contrasted their respective religions and cultures with that of the Western world by weighing the importance of economic and religious factors, among others, on historical outcomes. Weber resumed teaching in 1918. He intended to publish additional volumes on Christianity and Islam, but he contracted the Spanish flu and died in Munich on June 14, 1920. His manuscript of Economy and Society was left unfinished; it was edited by his wife and published in 1922.