The crux of the Chandogya Upanishad is found in the 6th Chapter wherein the famous Mahavakya - Tat Tvam Asi is declared. 

Here the Upanishad presents Brahma Vidya (the knowledge of the Supreme Truth) in a drama-dialogue style, as a discussion between the Guru-father, Uddalaka Rishi and his son-disciple, Shvetaketu.

The central teaching of Vedanta - the oneness between the individual and the Supreme Truth, is brought home by striking similes and apt metaphors.

Swamini Vimalananda has a good grasp of the subject. Her style of narration makes the text easy to understand. Her lucid notes are sure to benefit the reader.