Siddhars/Rishis are saints in India, mostly of the Saivaite denomination in Tamil Nadu, who professed and practiced an unorthodox type of Sadhana, or spiritual practice, to attain liberation. Yogic powers called Siddhis are acquired by constant practice of certain yogic disciplines. Those who acquire these Siddhis are called Siddhas. These sidhars can be compared to Mystics of the western civilization. Siddhars are people who are believed to control and transcend the barriers of time and space by meditation (Yoga), after the use of substances called Rasayanas that transform the body to make it potentially deathless, and a particular breathing-practice, a type of Pranayama. Through their practices they are believed to have reached stages of insight which enabled them to tune into the powers hidden in various material substances and practices, useful for suffering and ignorant mankind. Typically Siddhars were saints, doctors, alchemists and mysticists all at once. They wrote their findings, in the form of poems in Tamil language, on palm leaves which are collected and stored in what are known today as Palm leaf manuscript, today still owned by private families in Tamil Nadu and handed down through the generations, as well as public institutions such as Universities all over the world.