Listen to a lecture explaining how in Patanjali's Yoga Sutra, brahmacarya is interpreted to mean sexual abstention and dissociation from sensual urges and behaviors, practices which are part and parcel of the ascetical path of the yogins. By coming to understand what Patanjali’s work is promising and how the text proposes one arrives at its conclusions, you will come to understand why the yogin is enjoined to sexual abnegation.