This article offers a study and translation of an important but understudied letter written by the famous Sufi Ibn (d. 638/1240) to the foremost theologian of his day, Fakhr al-Dīn al-Rāzī (d. 606/1210). After situating the letter against the backdrop of the general Rāzī 'polemic' which had emerged in Central Asia and Anatolia during the sixth/twelfth and seventh/thirteenth centuries (particularly in Persian Sufi writings), the article explores the manner in which Ibn Arabī attempts to convince Rāzī to channel his aspirations in the right direction-namely to empty himself of his reliance upon his discursive powers and turn to the Sufi path. In order to drive his point home, Ibn Arabī offers a fundamental distinction between knowledge gained by way of intellectual reflection and knowledge afforded by 'unveiling', taking as his point of departure Rāzī's own well-known crisis of certitude. The foregoing discussion then paves the way for a complete, annotated translation of this important letter.