A theoretical formulation integral to classical Sanskrit aesthetics, rasa is an emotional state that arises through a successful representation of bhavas, or emotive states, through an artistic performance. The Natyashastra of Bharata, dating to the early centuries CE, presents the earliest known theorisation of rasa in its sixth chapter. Rasa theory continued to be developed and modified through the mediaeval period, most notably by Abhinavagupta in his eleventh-century commentary Abhinavabharati.

Rasa is believed to be integral to the creation and appreciation of poetic, theatrical and visual art. Some theoreticians even argue that the experience of the rasa is the primary goal of art. The word itself translates literally to “juice” or “flavour”, and can be more broadly interpreted as the emotional flavour or experience of life. The rasas described in the Natyashastra are shringara (erotic), karuna (compassionate), raudra (wrathful), vira (heroic), hasya (comedic), bhayanaka (horrific), bibhatsa (odious), adbhuta (marvellous). Other rasas were added by theoreticians in the centuries after the Natyashastra was composed, with the most widely-accepted being shanta (peace).

Despite continuing debates and arguments over various aspects of rasa theory, rasa itself became the conceptual foundation for formulating artistic principles in mediaeval Sanskrit aesthetics. The Shilpashastras, for example, explicitly used the concept of rasas to dictate representational principles in visual art. Modern scholars have also interpreted mediaeval Indian architecture, painting and music as directly intended to invoke specific rasas.

The meaning and implications of rasa theory provoked considerable debate through the mediaeval period. Bhatta Lollata is credited with being one of the first to initiate a philosophical discussion on rasa theory through his ninth-century text Utpattivada, a commentary on Bharata’s concept of rasa. Anandavardhana’s Dhvanyaloka introduced the concept of dhvani (‘utterance’ or ‘resonance’) and applied rasa theory to literary analysis, arguing that the objective of poetry was to manifest rasa. The theoretician Bhatta Nayaka later refuted Anandavardhana’s formulation by arguing that rasa was an aesthetic experience that belonged only to a viewer or reader, and that it could not be manifested through art itself. Though these texts have not survived, the substance of their debates were outlined by the influential Kashmiri aesthetician Abhinavagupta in his commentaries on the Natyashastra and Dhvanyaloka. Abhinavagupta’s work went on to present rasa as a mental state manifested in and experienced by the viewer or reader.

The means by which rasas are invoked have also led to much theoretical discussion. In the Natyashastra and commentaries such as those of Abhinavagupta, practitioners are enjoined to use the abhinayas angika (movement), vachika (speech), and aharya (costumes, makeup and other paraphernalia) to evoke sattvika bhava (internal emotions) and vyabhichari bhava (transitory emotions). These bring forth a sthayi bhava (dominant emotional state), leading to an experience of the corresponding rasa.

It is difficult to gauge the precise extent to which such theoretical models may have influenced practitioners and artists in the mediaeval period. Sanskrit poets are known to have developed a repertoire of compositional techniques, each held to be efficacious at evoking particular rasas; however, little evidence survives from other artists. Occasional innovations to rasa theory were developed in the late mediaeval period, with grammarians such as Vopadeva presenting devotion towards Krishna as an aesthetic experience akin to rasa in his commentary on the Bhagavata Purana. By the early modern period, references to rasa theory were less frequent, though it appears to have had some influence on the aesthetic theology of Gaudiya Vaishnavism.

Scholars have argued that contemporary Indian classical dances rely on abhinaya and nrtya to evoke rasa; classical music is also believed to manifest rasas through the use of ragas, each associated with a different rasa.