Siddhanta

Siddhanta is a Sanskrit term meaning an established doctrine, system, or truth. In Indian scholarly usage it denotes a formally authored treatise that presents a particular field of knowledge, or a school of thought within a discipline. The word is used across religious, philosophical, mathematical, and astronomical literature.

In astronomy and mathematics, siddhānta denotes a class of authoritative treatises that lay out models of celestial motion, calendrical rules, and computational methods. These texts often synthesize astronomical theory with ritual and cosmological concepts, and were used by scholars, astrologers, and temple priests across medieval and early modern India. Surya Siddhānta is among the best-known examples of this tradition, dating from late antiquity to the early medieval period and exerting wide influence.

Another prominent example is the Siddhānta Śiromani, attributed to Bhāskarācārya II (Bhāskar) in the 12th century. It comprises four parts, including Lilavati (arithmetic) and Bijaganita (algebra), with sections on astronomy and celestial calculations. The work became a standard reference in Indian mathematics and astronomy and influenced later developments in both Indian and Islamic astronomy.

Beyond astronomy, siddhānta can also mean a philosophical or doctrinal system in Hinduism, Jainism, and Buddhism, referring to an established set of theses or a school’s authoritative position.