This can be said to be the greatest of all Upanishads, not only in size but also in regard to the substance and theme it deals with. Shankarachaya's commentary on it is also the greatest of all his commentaries. The volume contains the text in Devanagari, a lucid and faithful translation of the text and commentary, relevant notes, references to quotations, and an index. All this makes this book indispensable to the students of Vedanta, especially those who are deficient in Sanskrit language, for a easy and correct comprehension of the subject.
The human soul has sojourned in lower and higher forms, migrating from one to another according to the samskaras or impressions, but it is only in the highest form as a human being that it attains to freedom.
-Swami Vivekananda