More than one of the Buddhist or Vishnuist mystical schools continued to employ the yogico-tantric maithuna (coitus) even when “devotional love” evidently played the essential rôle. The profound mystical movement known as Sahajiya, which continues tantrism, and which, like tantrism, is as Buddhist as it is Hindu, still accords their old priority to erotic techniques. But, as in tantrism and Hatha Yoga, sexual union is understood as a means of obtaining “supreme bliss” (mahasukha), and it must never end in seminal emission. Maithuna makes its appearance as the consummation of a long and difficult apprenticeship. The neophyte must acquire perfect control of his senses, and, to this end, he must approach the “devout woman” (nayika) by stages and transform her into a goddess through an interiorized iconographic dramaturgy. Thus, for the first four months, he should wait upon her like a servant, and sleep in the same room with her, then at her feet. During the next four months, while continuing to wait upon her as before, he sleeps in the same bed, on the left side. During a third four months, he will sleep on the right side, then they will sleep embracing, etc. The goal of all these preliminaries is “autonomization” of sensual pleasure, which is regarded as the sole human experience capable of bringing about the nirvanic bliss and control of the senses—that is, arrest of semen.

From Mircea Eliade’s Yoga: Immortality and Freedom, Princeton and Oxford: Princeton University Press, 2009 (first published in 1954), p. 266.