Śivasaṃhitā 4.73

The urinary control technique described here — retaining and releasing urine with conscious attention — is a secondary Vajrolī sādhana that works on the urinary system as preparation for seminal control. The physiological principle is the same: mastery of the urethral sphincter under voluntary conditions trains the neurological mechanism needed under conditions of high sexual arousal.

Apānavāyu is here the agent of urinary retention: the same wind governing excretion can, through practice, be directed to retain rather than expel. Śanaiḥ śanaiḥ — ‘slowly, slowly; step by step’ — is the gradual release instruction that appears frequently in the Śivasaṃhitā to signal that control is not abrupt blocking but gentle, conscious regulation of flow.

Vindu-siddhi — ‘the perfection of bindu’ — is here synonymous with total control over the reproductive-urinary system at an energetic, not merely physical, level. The ‘great powers’ (mahāsiddhi) this practice promises include in the tradition mastery over the anabolic processes of the body: one who controls vindu controls ojas, and one who controls ojas controls the aging process. Practice according to the guru’s instructions (gurūpadeśataḥ) is a sine qua non condition: without direct transmission, the technique can produce unexpected side effects.