This tale succinctly puts the perspective of self restraint in a yogi's life.
Kamadeva makes Lord Brahma fall in love with his own daughter Saraswati. Upset at his own passion, Brahma curses the god of love, to be burnt by Lord Shiva.
When Lord Shiva becomes an ascetic, the asura Taraka becomes invincible. His austerities had won this asura near-immortality because he could only be killed by Shiva's son. And with Shiva in an ascetic mood it seemed there would be no son in the near future. This meant Taraka's reign of terror would continue. But Indra plots to get Shiva interested in Parvati and sends Kamadeva, with his wife Rati (goddess of beauty) and Vasanta (representing spring) to do the needful. When Kamadeva's arrow hits Shiva, the ascetic becomes interested in Parvati. But realizing that it was Kama's arrow that broke his meditation, Shiva opens his third eye, reducing him instantly to ashes.
Then Rati's plea wins Kama back to life, but this time without a form, as Ananga, the one without a body, the pure one. Simply put, it means when passion is reduced to ashes (due to the power of one's penance or yoga) it revives itself as a sublimation, having shorn itself of its baser instincts.
When passion is there, but without the attributes that are normally associated with it, then it is something else...
I like to think my yoga practice should be going that way..
but I pray that my teaching also heads that way, then the message in this story would be an experience and a reality.. where I am not bothered about students' own slideback.. that will be day..