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.
After every happiness comes misery; they may be far apart or near. The more advanced the soul, the more quickly does one follow the other. What we want is neither happiness nor misery. Both make us forget our true nature; both are chains--one iron, one gold; behind both is the Atman, who knows neither happiness nor misery. These are states, and states must ever change; but the nature of the Atman is bliss, peace, unchanging. We have not to get it, we have it; only wash away the dross and see it.
-Swami Vivekananda