In his Treatise on Sentences and Words, the grammarian Bhartṛhari (ca. 450 CE) takes up the distinction between primary and secondary meaning in more detail than previous grammarians such as Pāṇini and Patañjali. His work is difficult—he is aware of, and engages with, Buddhist, Jaina, and Mīmāṃsā views of language, but not in a straightforward dialectical manner, as is the style of many other Indian thinkers. This causes controversy over his established views (for discussion of which see Cardona 1999). In terms of his position on the division between primary and secondary meaning, the interpretive debate centers on the implications of the sphoṭa-theory for the possibility of such a distinction.