The text nobody actually reads
The Vijnanabhairava Tantra lists 112 dharanas, meditative techniques for dissolving the boundary between individual awareness and universal consciousness. One asks you to feel the precise moment between inhaling and exhaling, and stay there. Another instructs you to contemplate the sensation of desire at its exact point of arising, before it becomes an object. A third asks you to imagine the universe as your own body, and then slowly let the imagining drop. None of these involve a partner. None of them are erotic. The Vijnanabhairava Tantra is a rigorous phenomenology of attention, composed in Kashmir sometime between the 8th and 10th centuries, and it is the closest thing Tantra has to a foundational document. Most people who have strong opinions about Tantra have never heard of it.