That which purifies, i.e. that which cleans up the toxins such as anger, ego, attachment, greed and excessive indulgence in sensual pleasures. That which helps in clearing up the barriers in the way of ongoing success in life. Verily, there is no purifier on earth equal to knowledge/awareness. A person who becomes perfect in yoga ( see the definition in glossary) finds it within himself/herself in the course of time. This knowledge, referred herein, is a combination of the intellectual and intuitive knowledge (Science and Self)as a purifier.