Chandogya is the most intriguing of all the Upanishads. It begins with directing the priests of a Soma-yaga to see the hidden wisdom-significance in what they perform and recite as a brute ritual. This sublimating of ritualism gradually leads us to perceiving the entire life system as a yajna held in and performed by Brahman. The next step this perception leads us to is "sarvam khalvidam brahma" (everything here indeed is Brahman). Then the enquiry as to what this Brahman is, begins. The answer we arrive at is "tat tvam asi" (That thou art). Finally we realize "atmaivedam sarvam" (atma indeed is everything here, or myself indeed is everything here). From this self-identity with "everything," with Brahman, we never return to our identity with individuated forms pertaining to the world of becoming.
The present commentary explicates in a lucid way how thinking progresses in this Upanishad, along with unravelling its schematic, structural and dialectical intricacies, both subjective and objective, both universal and particular.