Whatever the number of capacities, they can be characterized functionally; in fact, the term function (vyāpāra) or operation (vṛtti) is often used in place of the word for capacity more generally. In attempts to enumerate the capacities, philosophers consider questions such as what the basis of a linguistic function might be, and whether they are one-to-one or one-to-many functions (Ganeri 2006). Discussion of linguistic functions is important for understanding epistemology, a topic of interest primarily to Philosophy in contrast to Grammar and Aesthetics (see the entry on epistemology in classical Indian philosophy). These thinkers focus on how testimonial uses of language are authoritative ways of knowing (pramāṇa), whether in ordinary discourse or religious discourse such as the Vedas or the Buddha’s speech. For one example, consider Nyāya (“Reasoning”). In the Nyāya root text, Nyāyasūtra (NS), attributed to Akṣapāda Gautama (ca 200 CE), speech is defined as the assertion of an authoritative person (NS 1.1.7). Since the cognitions resulting from testimony are an important basis for acting, Nyāya philosophers are concerned with what hearers understand from speech, in particular, from nouns (NS 2.2.56). It is in this context that they take up the relationship between primary and secondary meaning, and the basis for figurative language use. Specifically, they are concerned with whether the principal referent of a noun is—a generic property, a particular thing, or some combination (their preferred view).