The first chapter contains the story of Naciketas and Yama; the second chapter teaches the path to liberation; the third chapter relates to Jivatma and the Paramatma; the fourth to sixth chapters contain the conclusion and verses on rebirth.The Katha Upanishad is one of the mukhya (primary) Upanishads and is also notable for first introducing the term yoga (lit. "yoking, harnessing") for spiritual exercise.