[4] The pioneer of modern yoga, Krishnamacharya, gives impractical instructions for the mudra, demonstrating in Norman Sjoman's opinion that he had never tried the practice.
[11] The practice has been proposed to serve to clean the bladder by drawing liquids towards the urethra as an auto-enema, similar to the intestinal shatkarma of basti.
[12] Among early Shaivite hatha yoga texts, celibacy and Vajroli are described only in the Shiva Samhita; its practice is omitted from the Amaraugha, the Yogabīja, and the Yogatārāvalī.
[13] The Amaraugha says that Vajroli is attained, presumably with samadhi, when the mind has become pure and the sushumna nadi, the central channel, has been unblocked to allow breath to flow freely.
Opposing the predominant religious culture of her nation at the time, fundamentalist Protestant Christianity, Craddock was struck by the Shiva Samhita's account of Vajroli mudra, with "the idea that sexual union could facilitate divine realization".
The yoga scholar Andrea Jain notes that Craddock's "sacralization of sexual intercourse"[3] is far from radical by modern standards, but it was "antisocial heterodoxy" in the 1900s, leading indeed to her "martyrdom".
[3] The British Orientalist John Woodroffe describes the ability of a yogi to draw air and fluid into the urethra and out, and says, "Apart from its suggested medical value as a lavement of the bladder it is a mudra (physical technique) used in sexual connection whereby the Hathayogi sucks into himself the forces of the woman without ejecting any of his force or substance—a practice which is to be condemned as injurious to the woman who 'withers' under such treatment"[14] The explorer and author Theos Bernard illustrates himself in a posture named Vajroli mudra in his 1943 participant observer book Hatha Yoga: The Report of a Personal Experience.
[15] Bernard states that he was instructed to learn this once he could do lotus position (Padmasana) so that he would be strong enough to use it "in the more advanced stages" of his hatha yoga training; there is no suggestion in the book that he followed the full practice.
"[5] The magazine of Satyananda Saraswati's Bihar School of Yoga, noting the criticism of Vajroli mudra, defends the practice in a 1985 article.
It states that the Shatkarma Sangraha describes seven Vajroli practices, starting with "the simple contraction of the uro-genital muscles and later the sucking up of liquids".
Similarly, Singleton notes, the leader of Arya Maitreya Mandala in Europe, Hans-Ulrich Rieker called these three practices "obscure and repugnant"[19] and omitted them from his 1957 translation of the Hatha Yoga Pradipika.