The Tamil Siddhas are a religious order of mystics found in the southern part of India
Their origins can be traced back to the eighth century. They form a distinctive part of a larger movement which spread throughout South Asia, from Sri Lanka in the South to Tibet in the north, between the seventh and eleventh centuries. Siddhas everywhere share common practices, cosmology, and symbols derived from Tantrism whether the practitioner is Hindu, Buddhist, or Jain. All are part of a "pan-Indian tantric yoga movement" which Eliade described as formulating over a five hundred year period, between the 7th and the 11th centuries, but fully flowering only after the 12th century.
Excluding perhaps the Buddhist Siddhas, all such groups are considered radical, if not dangerous, by the orthodoxy. An intriguing aspect of the Tamil Siddha cult is that it shares with the orthodox Saiva Siddhanta sect a common text that defines the philosophy of both groups. Since each sect emphasized different aspects of the teaching they quickly became widely divergent, with the two orders often at odds. The Siddhas would be scoffing at temple worship, reliance upon Brahminical authority, and proclaiming the injustice of caste; while the Saiva Siddhantins would berate the Siddhas much as M. Srinivasa Iyangar did in 1914 when he wrote that the Siddhas are "mostly plagiarists and impostors" and in addition, "Being eaters of opium & dwellers in the land of dreams, their conceit knew no bounds".
At times the Siddhantins have even engaged in an organized effort to eliminate the Siddhar faction. For example, one movement, observed in the latter half of the nineteenth century, systematically sought out any copy of the writings of the heretical Siddha-poet Sivavakkiyar, and promptly destroyed them.
Within the context of Hindu myth the name Siddha originally denoted one of the eighteen categories of celestial beings. These beings of semi-divine status were said to be of great purity and their dwelling was thought to be in the sky between the earth and the sun. Later they became associated with a class of more adept human being, often an accomplished yogi. The term had been derived from the Sanskrit root sidh meaning "fulfillment" or "achievement," so the noun came to refer to one who had attained perfection. Because the Tamil language lacks the aspirated consonants of Sanskrit the word has been written and pronounced by the Tamils as cittar. This has lead the Tamils to associate the word more with the Sanskrit term chit, meaning "consciousness."
Tamil Siddhas have been known as iconoclastic in their writings and tendencies. Here this misunderstanding is cleared andcorrect knowledge of the writings is given. For the first time also, the dasa diksa and gymnosophy of the Tamil Siddhas areadumbrated here in a new light, which the student of the Tamil Siddhas will appreciate. The author has attempted,successfully to prove some of the concepts and Yogic practices of the Siddhas by quoting from the Upanisads and explainingthem. The modern discoveries and medical science have helped him to assert the scientific and medical qualities of theprescriptions of the Siddhas for perfect health and steady spiritual progress. If the world of humanity today still carried asemblance of peace and well-being. It is by the Grace and Guidance of these Elders, the Siddha Brotherhood. May their Gracecontinue to guide humanity is the prayer in this study?