His Holiness Swamiji Sivananda Paramahamsa, the divine preceptor of preceptors. He is a native of North Malabar. This Vidya by itself is nothing new and Swamiji vouches that it had been practiced by our old forefathers while doing tapas in the forests and mountains of our blessed Motherland. By the passing away of those divine Rishis and Munis of old the Vidya had perhaps been gradually forgotten or mispractised in some form or other.
The blessed Guru, Swamiji Sivananda Paramahamsa, the Founder of Siddha samaj, who discovered the shortest and easiest way to self-realization, Kaivalya, Nirvikalpa Samadhi or moksha, has traveled all through India from Cape Comorin to Afghanistan, through forests and mountains, where, even at the present day, Rishis and Munis and other sadhus still do tapas.
Swamiji himself, after tedious and strenuous efforts, has found out the upward course of Jeeva (Urthva Gathi). It is nothing but Siddha Vidya, that in the words of Swamiji is life (Jeeva)-which is present in oneself, gets downward, spreads out and destroys-being not allowed so to spread out, should be ever conducted up and down inwardly, there by knock open the Brahmarandhra, and learn to unite the life there with Eswara (at Brahmarandhra).It is Siddha Vidya.
His Holiness
Swami Sivananda Paramahansa

Swamiji's Teachings
As the old saying goes, the more we advance towards Self-realization the less selfish we become. Having himself enjoyed the Supreme Bliss through his own efforts, Swami Sivananda Paramahansa wanted to promote and benefit the worldly people. Through his teachings he shows to the public where the Lords of Lords “DAKSHINA MURTHY” have his place of abode in us and also the easiest way to have a Darsan (Vision) of Him.
He makes no distinction of sex, caste or creed for his teachings to be followed and in order that the world may take advantage of his teachings and instructions he wrote a book called “SIDDHA VEDAM” in the year 1922 naming his vedam as the 5th vedam of the universe.
As per Swami, all learnings whatever it may be are meaningless if one does not realize himself. To realize one self one must learn himself Siddha Vidya is the art of learning oneself and knowing oneself is self-enlightment (or known as) Kaivalyam.

Jeeva Samadhi
Swami Sivananda Paramahamsa, who is the founder of Siddha Samaj was at Palani during his last days and as per his wish attained Jeeva Samadhi at Palani, Tamil Nadu. The place is located at a 5 min walking distance from the Palani Temple Girivalam route (at the foothill).
A very special place and must-visit location for people who are spiritually seeking self-realization. The auspicious site is having an Ashram named: Akhila Ulaga Siddha Vidya Abhivruthi Sangam. This ashram is in a bad shape and needs immediate rennovation and with the blessings of Swami its bound that the place will be restored to its deserving splendid state and will definitely be a boon to the Siddha Vidyarthis and future seekers of Self-realization.
Even though Swami attained jeeva samadhi at this very location, the jeeva samadhi was later taken to Siddha Samaj Ashram, Vadakara, Kerala (which happens to be the headquarters of Swami ji's Siddha Samaj. But, this holy place in Palani holds its grandeaur as it was the preferred choie of Swami for his Jeeva Samadhi. It is worth noting that its beleived that Swami Sivananda Paramahansa had been initiated to this holy science by none other than Bogar Siddhar (in his astral form). Palani is the place of Bogar's Jeeva Samadhi as well.

Video about teachings of Swami Sivananda Paramahansa by Siddhavedam.info (available in youtube)

Samadhi location of Swami Sivananda Paramahansa in Palani Ashram