This book contains the English translation of the aphorisms of Patanjali on the Yoga Sutras, running into nearly two hundred in number. It explains the theory of the science of Yoga as well as its techniques of controlling and purifying the three lower vehicles of man, namely, the body, the mind and the spiritual self. Further, it gives a detailed description of Antaranga Yoga, along with a list of psychic powers and the ways to acquire them. Finally, it deals with the Kaivalya or final emancipation. The Sankhya Pravacana Commentary of Vyasa and the Gloss of Vacaspati Misra also make part of the book.