The Middle Ages in Northern India were rich in religious reformist teachers propagating their doctrines in poetical form; the most talented of them were considered great poets in the Indian literary tradition. This paper deals with the problems associated with the ―codification‖ of the language of preaching mystical teachings in the 16th century in Northern India. The present review is confined to some aspects of the literary works of the nirguṇa-bhakti poet Kabīr (1440-1518) and the Sufi poet Malik Muhammad Jāyasī (1500-1558).