This book incorporates some of the practical lectures on devotion delivered by Swami Vivekananda. Here he discusses the preparatory disciplines, the importance of the guru and how to choose one, the principles of ritual worship, the chosen ideal, and finally, the supreme love. This book differs from the Swami's Bhakti Yoga lectures, not in subject matter, but in his treatment of the subject here in an intensive, yet more easily appreciable form.
The book one must read to learn natural sciences is the book of nature. The book from which to learn religion is your own mind and heart.
-Swami Vivekananda