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.
Those who work at a thing heart and soul not only achieve success in it but through their absorption in that they also realize the supreme truth -- Brahman. Those who work at a thing with their whole heart receive help from God.
-Swami Vivekananda