This entry deals briefly with the Isvara concept in the six schools of philosophy in Hinduism, usually called the orthodox schools because they were thought to believe in the authority of the Vedas. The schools are Nyaya, Vaisesika, Samkhya, Yoga, Purvamimamsa, and Uttaramimamsa, also called Vedanta. This article is not a philosophical discussion of the nature of Isvara but is a description of how Isvara is viewed in these schools.

Each of the main schools has a foundational text called sutras. The word sutra means "a thread" and is usually a brief sentence of a few words that convey the basic philosophy of the respective school. As these sutras are difficult to follow without some explanation, commentaries called bhasyas emerged from erudite commentators, which in turn spawned commentaries on commentaries that went on for a long time up until the...