Tamil Siddhas have been known as iconoclastic in their writings and tendencies. Here this misunderstanding is cleared and correct knowledge of the writings is given. For the first time also, the dasa diksa and gymnosophy of the Tamil Siddhas are adumbrated 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 explaining them. The modern discoveries and medical science have helped him to assert the scientific and medical qualities of the prescriptions of the Siddhas for perfect health and steady spiritual progress. If the world of humanity today still carried a semblance of peace and well-being. It is by the Grace and Guidance of these Elders, the Siddha Brotherhood. May their Grace continue to guide humanity is the prayer in this study.