Although the Atman is unknown to us now, is it unknowable? Can we experience it via our senses or through perception? The Atman does not fall within the range of our sense perception. Kathopanishad shares the method of gaining this knowledge; listening, reflecting and then meditating. The student needs a purified mind and to have gained knowledge from a Guru. When a qualified student approaches the teacher, the Guru gives the knowledge. That is called Shravanam. Once we have heard, Mananam or reflection is required to  slowly reduce the mind’s attention from external objects to the internal. And finally, meditation.
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