The author had quoted from this Upanishad and explained its ideas in several of his lectures, class-talks, and conversations. All this material, spread throughout the nine volumes of his Complete Works, has been brought together in this book for the first time. What makes this compilation a treasure trove of original ideas and masterly insights is that the author goes straight to the heart of the subject to focus on the essentials, and to evolve practical methods from abstract principles.
The whole universe is one in the Atman. That Atman when it appears behind the universe is called God. The same Atman when it appears behind this little universe, the body, is the soul. This very soul, therefore, is the Atman in us.
-Swami Vivekananda