There is the story of a king who, becoming thirsty after hunting in the forest, approaches a secluded hermitage in quest for water. He is greeted by a beautiful but spiritually edified young maiden who had been raised as a fully enlightened yogini by the resident sage of the hermitage. Overcome by desire for this beautiful maiden, the king propositions her. Deciding to enlighten the lusty king as to the realities of bodily yearning, the maiden requests him to return within a month, at which time she will allow him to taste the nectar of her beauty. During this period, however, the maiden takes laxatives and purges, and collects all the resulting vomit, urine, feces, and other discharges in earthen pots. When the king returns after the stipulated period, he is greeted by the maiden, now haggard and wasted and a shadow of her previous self. Upon asking her what had become of her beauty, she presents the king with the earthen pots with their rancid contents and indicates that therein lay the juices of her beauty.

From The Yoga Sutras of Patanjali, Translated with Commentary by Edwin Bryant, New York: North Point Press, 2009, p. 268.