Mysticism in India is a complete and informative description of the teachings, works, and lives of the great poet-saints of Maharashtra written by a scholar and professor who was also a mystic. Jnaneshwar, Namadev, Tukaram, Eknath, Ramdas, and the other saints discussed belonged to the great devotional religious movement that spread through medieval India. With the exception of Ramdas, they all belonged to the tradition of the Varkaris, the most popular sect in contemporary Maharashtra. Their compositions exemplify the universality of their faith and practice, and are recognized as literary treasures.

Ranade was primarily interested in the poet-saints as mystics—teachers of the perennial philosophy—whose experiences have general metaphysical and religious implications. At the heart of his classic is a comprehensive, objective presentation of the thought of these saints, augmented by a deep appreciation of their value and relevance to present-day scholars and seekers.

Mysticism in India is the only major study in English of medieval Indian religious literature. The book's enduring value has been enhanced by the addition of a foreword by a scholar currently working in Marathi literature, and a preface by a present-day poet-saint of Maharashtra.