All the orthodox systems of India philosophy have one goal in view, the liberation of the soul through perfection. The method is by Yoga. The word Yoga covers an immense ground, but both the Sankhya and the Vedanta Schools point to Yoga in some form or other. The subject of the present book is that form of Yoga known as Raja-Yoga. The aphorisms of Patanjali are the highest authority on Raja-Yoga.