What This Book Is
Rūpa Goswāmī, the senior of Caitanya Mahāprabhu's six Goswāmīs, completed the Bhakti-Rasāmṛta-Sindhu in 1541 in Vrindavan. He was about fifty-two years old. He had spent his prime as a minister in the Bengal court, met Caitanya, renounced the position, and walked to Vrindavan to do what Caitanya had asked: uncover the lost places of Krishna's pastimes, and give the prema he had brought a permanent grammar.
The Sindhu, the ocean, is the grammar. Four vibhāgas (divisions, named after the four directions) totaling roughly two thousand verses. Each vibhāga has multiple lahari, waves. The whole work is structured as an ocean with waves, fitting the title: the ocean of the immortal nectar of bhakti-rasa.
Within this ocean Rūpa accomplished what no Sanskrit text had attempted before: a systematic theory of devotional emotion as a kind of aesthetic experience. He took the rasa-shastra of Sanskrit drama (the dance and theater theory of Bharata Muni's Nāṭya-shāstra) and applied it to the inner life of the bhakta. The five primary rasas of devotion (peace, servitude, friendship, parental affection, sweet love) became a working taxonomy. Sweet love (mādhurya), the love of Rādhā for Krishna, became the supreme.