The Upanishads form the final portion of the Vedas which are considered the primeval source of the scriptures. Sage Badarayana Vyása classified them as Rik, Sáma, Yajuh and Atharvana Vedas. This book provides an exhaustive commentary on four Upanishads namely Kena, Isávásya, Kaivalya and Mundaka. The Upanishads expound a system of philosophy which helps humanity attain spiritual enlightenment.