English translations of all the Upanishads are not readily available. Most of the pundits have translated only the principal Upanishads. Four translations from which passages have been cited in this book are Sixty Upanishads (translated from Paul Deussen's German version to English by V.M.Bedekar and G.B.Palsule), Principal Upanishads (by Dr. S.Radhakrishnan), Upanishads (New Translations by Patric Olivelle, Oxford University Press. 1996) and Eight Upanishads (translated by Swami Gambhirananda of Advaita Ashrama). Borrowed texts have been acknowledged when quoted. Other translations are by the author