Vachaspati Mishra was a 9th century Indian hindu philosopher of the Advaita Vedanta tradition. He wrote so broadly on various branches of Indian philosophy that he was known as "one for whom all systems are his own", or in Sanskrit, a sarva-tantra-sva-tantra. Vācaspati Miśra was a prolific scholar and his writings are extensive, including bhasya (commentaries) on key texts of almost every 9th-century school of Hindu philosophy with notes on non-Hindu or nāstika traditions such as Buddhism and Carvaka. He also wrote one non-commentary, Tattvabindu, or Drop of Truth, which focuses on Mīmāṃsā theories of sentence meaning. Some of his works are lost to history or yet to be found.
Little is known about Vācaspati Miśra's life, and the earliest text that has been dated with certainty is from 840 CE, and he was at least one generation younger than Adi Śaṅkara. However, an alternate date for the same text may be 976 CE, according to some scholars, a confusion that is based on whether Hindu Śaka or Vikrama era calendar is used for the dating purposes. His scholarship is revered in the Hindu tradition, which believes that he was a Maithil Brahmin from Andhra Tharhi Bihar. It is believed that the name of his most famous work "Bhamati" was inspired by his devout wife.
Tattvabindu is his original work, wherein he develops principles of hermeneutics, and discusses the "Theory of Meaning" for the Mīmāṃsā school of Hindu philosophy. This is an influential work, and attempted to resolve some of the interpretation disputes on classical Sanskrit texts.
Vācaspati concurs with the Bhāṭṭa view, when he employs in other contexts, such as the Nyāya sub-commentary, the Nyāya-vārttika-tātparya-ṭīkā, and the Tattva-vaiśāradī.
Vācaspati Miśra is credited with influential commentaries such as Tattvakaumudi on Sāṃkhyakārika, Nyāyasucinibandha on Nyāya-sūtras, various important texts of Advaita Vedānta, Nyāyakānika (an Advaita work on science of reason), Tattvasamikṣa (lost work), Nyāya-vārttika-tātparyaṭīkā (a subcommentary on the Nyāya-sūtras), Tattva-vaiśāradī on Yogasūtra, and others.
While some known works of Vācaspati Miśra are now lost, others exist in numerous numbers. Over ninety medieval era manuscripts, for example, in different parts of India have been found of his Tattvakaumudi, which literally means "Moonlight on the Truth". This suggests that his work was sought and influential. A critical edition of Tattvakaumudi was published by Srinivasan in 1967.