Sanat Kumara is one of the four sons created from the mind of Lord Brahma the creator. Once while meditating in Brahma Loka (Abode of Lord Brahma), he had a vision of fighting against the Asuras. Being a Bramha Jnani (A Self realised soul) who has transcended all the pair of opposites, he was perplexed and wanted an answer from Lord Brahma. The Lord explained that as a Brahmana in his previous birth, he had witnessed Asuras destroying his ashram and in his anger he wanted to destroy them. That thought is the reason behind this dream. The Lord assured him that there may be a purpose behind this dream since the dream of a Jnani should come true.Later, once Lord Shiva and Parvati visited Brahma Loka. Lord Brahma welcomed them with great reverence and happiness. Unmoved by the Lord’s divine presence Sanat Kumara continued his meditation. Lord Shiva was very much pleased by his Brahma Jnanam and blessed him with a boon of his choice. Sanat Kumara politely declined it as he had no need for a boon. Then Lord Shiva asked him to grant a boon for himself which he immediately agreed upon. Lord Shiva asked him to be born as his son which was accepted by Sanat Kumara on a condition that he should be born to Shiva alone without the involvement of Mother Parvati as Lord Shiva was the one who asked for the boon. Parvati Devi was immensely annoyed by this request but got pacified as she realised that there was a purpose behind this.
Lord Subrahmanya was born from the six sacred sparks emanated from the divine third eye of Shiva in the month of Vaishaka and his birth star was Vishaka. The fire god Agni carried the sparks and deposited them in the Sharavana pond and six divine babies were born in a lotus flower who were nursed by six celestial Karthika women. Later Mother Parvati hugged them all and they turned into one child with six faces.
The demon Taaraka had a boon that he should be killed by a person born without the involvement of a woman in the process and so Sanat Kumara’s conditional boon has served its purpose when he killed the demon.
