In Upanishads is articulated not only the quintessence of spiritual wisdom, but also the remarkable philosophical genius of the classical Hindu mind. Owing, however, to their complexity, metaphor, and even obscurity, Upanishadic writings have been endlessly debated, discussed and written upon, more specially since Shankara’s time. Swami Narayana Prasad’s commentary is yet another valuable addition to the existing literature attempting, as it does, to rationally unlock the metaphysical subtleties of Prashna Upanishad — with the master-key handed down to him in the disciplic succession of Sri Narayana Guru. Prashna Upanishad offers an enlightened exposition of brahmavidya: knowledge of the Absolute/Supreme Reality. In an aptly thought-out dialectical situation, it offers a threadbare discussion of six questions which, centreing around procreation/origin of beings, prana: the most vital life-sustaining principle, functional states of the Self (purusha), significance of meditating on AUM — lead to the finality of Vedantic wisdom: the sublimity of non-dual Reality: the param purusha of sixteen kalas.