The "King of Saints" was Jnaneshwar (?1271-1293), who, while living only twenty-two years, made an indelible mark on the whole of Hindu spirituality. Before Jnaneshwar's time, the scriptures of India were in the secret language of Sanskrit and completely unavailable to the lower classes. Breaking from tradition, Jnaneshwar not only translated the central Sanskrit text, the Bhagavad Cita, into the common language of Marathi but added a magnificent commentary which expounds the complete path of yoga and spiritual practice. His commentary, the Jnaneshwari, still stands among the greatest spiritual works ever written.
Source : Jonathan Star, The Inner Treasure