Towards this goal he completed the translation of fifty Upanishads from their original Sanskrit into Persian in 1657 so that they could be studied by Muslim scholars.[42][43] His translation is often called Sirr-e-Akbar ("The Greatest Mystery"), where he states boldly, in the introduction, his speculative hypothesis that the work referred to in the Qur'an as the "Kitab al-maknun" or the hidden book, is none other than the Upanishads.[44] His most famous work, Majma-ul-Bahrain ("The Confluence of the Two Seas"), was also devoted to a revelation of the mystical and pluralistic affinities between Sufic and Vedantic speculation.[45] The book was authored as a short treatise in Persian in 1654–55.[46]