The pursuit of alchemical knowledge for the Muslim literati of the Ottoman Empire still revolved around the long-established classics by the end of Suleiman I's reign in 1566: the vast Jabirian corpus, the individual works of, among others, al-Razi, Ibn Umayl al-Tamimi, Abu'l-Qasim al-'Iraqi, and 'Izzaddin Aydemir al-Jildaki, in addition to a number of important apocryphal treatises attributed to certain historical and mythical characters. Half a century later, these works had been joined - and in some cases even supplanted - by the Arabic and Turkish corpus of Eshrefzade 'Ali Chelebi (d. 1609). A maternal descendant of Eshrefzade 'Abdullah Rumi (d. 1469), the founder of the Eshrefiyye branch of the Qadiriyye Sufi order, 'Ali Chelebi was born and educated in Izniq, but eventually settled in Istanbul around the turn of the seventeenth century. The hitherto unstudied corpus consists of more than twenty alchemical works that have survived to the present in numerous manuscript collections scattered throughout a vast geography stretching from Morocco to India, and which won their writer the epithet al-mu'allif al-jadid (the new author). This paper will socially and historically contextualize the figure of 'Ali Chelebi and some key aspects of the works ascribed to him. More specifically, the often-articulated links between Islamic mysticism and the (re)production of alchemical knowledge will be explored for the early modern Ottoman society, with a focus on 'Ali Chelebi's Sufi connections and on the identities of the known copyists of his writings. In this context, the paper will also dwell on the important notion of secrecy--using the period's alchemical literature, as well as its hagiographies, the inherent epistemological tension between occultation and disclosure in the teaching of esoteric sciences will be probed. It will moreover be shown that late in his life, 'Ali Chelebi chose to transgress the established boundaries between the esoteric and the exoteric; an attempt to answer the difficult question of why there was an explicit intent, on the part of the author, to render alchemical secrets "public" will be made based on the wider circumstances surrounding the corpus's composition.