Who is a siddha ? A siddha is one who has attained siddhi, i.e. "power, prowess, strength, ability", then a special kind of psychic and supernatural, miraculous, occult power. There are eight kinds of super natural powers called as "Ashtama Siddhis":
A classical definition of siddhas is given by Siddhar Thirumoolar: "Those who live in yoga and see the divine light and power through yoga are the siddhars (Tamil Chittar)".
According to Kamil Zvelebil, there are some features which are typical for all or almost all siddhars as a body of thinkers.
The whole atmosphere of siddha thinking is empirical and experimental. Their writings are not in the nature of clear cut formalized statements of any well defined doctrine. Hence, it is difficult to extricate a philosophical system out of their writings, at least at the present state of our knowledge of their works. However, it is possible to point out a few essential features, and one day, when their writings are better known, it should be possible to state their philosophy more explicitly.
This web site is devoted to publishing the works of siddhars for the internet community. Most of the works are available only in Tamil and it is possible that the author of document interprets things in his own way while translating the original text. An attempt is made to present information about siddhars here.
Chapter Eighteen (Pages 364 & 365) of book entitled "Eighteen Siddhars in History of Siddha Medicine" by Mr. N. Kandasamy Pillai, Former Member, Siddha Science Development Committee and Published by the Government of Tamil Nadu in 1979.
Chapter Fourteen (Pages 224 & 225) of book entitled "The Smile of Murugan of Tamil Literature of South India" by Kamil Zvelebil and Published by E.J. Brill, Leiden, Netherlands in 1973 (ISBN 90 04 03591 5).
Song 1490 of "Thirumandiram Moovayiram" by Siddhar Thirumoolar.