This present book is a classic among the various works of Swami Sivananda, for it contains the teachings and experiences of the ancient seers and sages. Rendered in a simple and lucid style by profuse explanations and commentaries, through the forceful and inimitable pen of the illustrious author and Sage of the Himalayas, this book is a guiding light for all the seekers on the spiritual path. The teaching of this book have their basis on direct experiences of the sage-author. It is due to this reason that every word, every sentences of this marvelous book enters right into the heart of the reader and has a message to transform his life. It is an inspiration to strengthen his steps to God- realization. May this book be an inspiration and light unto all. May the blessing of His Holliness Sri Swami Sivanandaji Maharaj illumine your path.