J. J. M. (Jan Jakob Maria) de Groot, Ph.D., (1854-1921) was a Dutch Sinologist and historian of religion. In this scholarly book published in 1910, he details the history, rituals, and beliefs of the major traditional religions of China: universal animism, polydemonism, specters, ancestral worship, Confucianism, Taoism, and Buddhism. He thought that one spiritual essence could be detected beneath a great variety of religious, philosophical, and even political expressions in China, and his lifework was the discovery and exposition of that essence.
Jan Jakob Maria de Groot (18 February 1854 – 24 September 1921) was a Dutch sinologist and historian of religion. He taught at Leiden and later in Berlin, and is chiefly remembered for his monumental work, The Religious System of China, Its Ancient Forms, Evolution, History and Present Aspect, Manners, Customs and Social Institutions Connected Therewith. The two "books" of this detailed and well-illustrated treatise appeared in six volumes - and, according to the preface in the first volume, the System was originally meant to include several more "books".