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 have succeeded in attaching or detaching their minds at will have succeeded in Pratyahara, which means gathering towards, checking the outgoing powers of the mind, freeing it from the thralldom of the senses. When we can do this, we shall really possess character; then alone we shall have taken a long step towards freedom. Before that, we are mere machines.
-Swami Vivekananda