Sovereign Tantra in Four Parts (Catuṣpīṭhatantra, Rgyud Gdan bzhi) is linguistically one of the most enigmatic scriptures of its kind. Fortunately, Bhavabhaṭṭa's commentary, An Aide-memoire (Smṛtinibandha, Dran pa’i rgyumtshan), has survived in both Sanskrit and Tibetan translation. Without this text, many of the tantra's mysteries would remain inaccessible. Bhavabhaṭṭa, a renowned 10th-century scholar active at the Vikramaśīla university, offers a detailed, clear, and authoritative treatment of the text. His commentary was highly influential, remaining in use at his monastery even two centuries later. Bhavabhaṭṭa’s broader project involved commenting on the key yoginītantras of his time, including the Vajraḍākatantra and the Herukābhidhāna/Laghuśaṃvara, the latter being his most developed work. His interpretations were likely regarded as the definitive commentaries on these complex and significant scriptures.

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