9.2 राजविद्या the king of sciences, राजगुह्यम् kingly secret, पवित्रम् purifier, इदम् this, उत्तमम् highest, प्रत्यक्षावगमम् realisable by direct, intuitional knowledge, धर्म्यम् according to righteousness, सुसुखम् very easy, कर्तुम् to perform, अव्ययम् imperishable.

Commentary:
In this verse Lord Krishna eulogies the knowledge of Brahman very highly in order to create a great interest in the spiritual aspirants for attaining It ickly.There is neither blind faith nor faithmongering in this royal science. The truth, the sovereign,secret (the Self or the Absolute) can be directly realised by intuition or immediate perception. The science of the Absolute is the most splendid of all sciences. It is the science of sciences. Of sciences the highest, of secrets the most profoun, of purifiers the supreme is this. The knowledge of Brahman is the best purifier. It reduces the roots of all Karmas and all the Karmas themselves which have been stored up in the course of many thousands of births, into ashes in the twinkling of an eye. It destroys Avidya along with its effects. An expiatory act (Prayaschitta) cannot destroy all sins. It removes the effect of a single sin, only to some extent. Even if it is removed the effect of that sin remains in a subtle state in the mind and forces him to do sinful acts in his next birth. But the knowledge of the Self destroys ickly all the sins in their gross and subtle states that are accumulated in the course of several thousands of births along with Avidya, their cause. That is the reason why it is a supreme purifier. The causal body of the Jiva is called MulaAvidya (rootignorance). The Avidya or the veil of ignorance that envelops the visible objects of this world is called Sthula Avidya or gross ignorance.The knowledge of the Self is not opposed to Dharma. It is the fruit of all actions done in many births without expectation of fruits. Further, the knowledge of the Absolute can very easily be attained. One may think that this knowledge will perish soon as it is easily obtained, when its effect is exhausted. It is not so. It is imperishable. It is everlasting. It shines for ever by its own Selfeffulgence. He who has tasted this nectar even once becomes immortal. Therefore the knowledge of the Absolute is certainly worth aciring. You will have to strive very hard to attain it anyhow in this birth, as it is very difficult to get a human birth. Strive hard every moment, for life is uncertain and the prize (final liberation) is great.