UMĀPATI ŚIVĀCĀRYA (fourteenth century CE) was a Tamil Śaiva Siddhānta teacher, author, and theologian. Umāpati Śivācārya, who flourished in the South Indian temple city of Chidambaram during the early fourteenth century, was the last of the four santāna ācāryas ("hereditary teachers," a term here referring to four theologians in teacher-disciple succession) of the Tamil Śaiva Siddhānta school of philosophy-theology. (The other three ācāryas were Meykaṇṭār, Aruṇanti, and Maṟaiñāṉa Campantar, all of whom lived in the thirteenth and fourteenth centuries.) According to tradition, Umāpati was a Vaiṣṇava brahman from Koṟṟavaṉkuṭi, near Chidambaram. One day, coming from the temple, he encountered the Śaiva ācārya Maṟaiñāṉa Campantar. This...