Jnana-yoga or "The Path of Knowledge" is one of the four central paths to knowledge of man and the world and realization of the ultimate reality as obtained in the ancient religious and philosophical traditions of India. It is the way of overcoming doubt through the exercise and development of the buddhi (the discriminative intellect). The roots of this tradition are traced to the glorious Upanisads; and the earliest jnana-yogis are none other than the Upanisadic rsis themselves. In this book, the author presents the fundamental insights of jnana-yoga based upon the teachings of two of the most prominent jnana-yogis __ Sankara, the Hindu philosopher, poet and mystic and Nagarjuna, the Buddhist philosopher and patriarch.
A result of Prof. Puligandla's theoretical and experimental study of their teachings for over three decades, the book systematically discusses in clear and unambiguous terms three central principles of jnana-yoga, namely, the principle of Superimposition; the principle of Dependent Origination; and the principle of Two Truths. The broad-based approach of this work is evident in many ways as, for instance, in its use of the principles of modern science to illustrate the ideas of jnana-yoga and discussion of concepts of the western philosophical tradition as well.
The book would immensely aid scholars of religious-philosophical traditions as well as students studying Indian traditional systems of thought.
This is one of the most useful books I've read on the topic of Jñāna-yoga -- the approach to yogic philosophy employed by the studious / inquisitive (in contrast to Bhakti-Yoga [the yoga of those for whom faith and devotion works] and Karma-Yoga [the yoga for those for whom a course of self-less action appeals.]) There are Jñāna-yogic Hindu sects and Buddhism -- in general -- can be thought of as a school of Jñāna-yoga. The author draws from the teachings of both, principally Sankara for Hindu thinking and Nagarjuna for the Buddhist approach.
A word of warning, the author is a scholarly philosopher, and so -- while not as unreadable as many works of academic philosophy -- it will be a slog for those who are not used to reading scholarly writing.
That said, Puligandla does a fine job of laying out what he views as the central tenets of Jñāna-yoga in a concise fashion and reviewing them at the end. This is not to say I would agree with all that he proposes, herein. In particular, his Chapter 3 conclusions about consciousness are insufficiently justified to be considered core principles of Jñāna-yoga (in my view.) Of course, the beauty of Jñāna-yoga is that it not only doesn't insist upon coming to the same conclusions, it generates explanations as to how it's perfectly possible / reasonable to come to different conclusions (see "The Principle of Superimposition," herein.) Furthermore, since the author is reporting the ideas of Sankara and Nagarjuna, I can't really hold these ideas against him.
If you're interested in Jñāna-yoga, and can handle scholarly prose, I'd highly recommend this book.