Max Muller, The Upanishads, The Sacred Books of the East – Part 1, Oxford University Press, Quote: (He who engages in) self study, concentrates all his senses on the Self, never giving pain to any creature, except at the tîrthas, he who behaves thus all his life, reaches the world of Brahman, and does not return, yea, he does not return".
GN Jha: Chandogya Upanishad VIII.15, page 488