Being A “Fususi”: Muhyi-i Gülseni’s (d. 1603/1604 C.E.) Intellectual World and Defense of Ibn al-Arabi Muhyi-i Gülseni is known in today’s Ottoman Sufism and historical scholarship mainly as the meticulous hagiographer of Ibrahim-i Gülseni (d. 1534)—the founder of Egypt based Halvetiye-Gülseniye order of dervishes. Muhyi lived most of his adult life in the Cairo lodge-complex with his spriritual mentor, Gülseni’s son, and successor Ahmed-i Hayali. Being part of an extensive Gülseniye network, he traveled regularly in the wider Ottoman geography meeting with other members of the order while his master was alive. After Hayali’s death, Muhyi reached an important position in the Cairo lodge. Subsequently he began establishing intimate connections with select members of the Ottoman ruling elite in Istanbul—such as Sultan Murad III. His copious literary production played a significant role in Muhyi’s popularity at court. Indeed, Muhyi was a prolific writer who authored over two hundred texts spanning from works on ethics, grammar, hagiography, counsel for sultans, and mystical poetry. Baleybelen—the Esperanto-type language—and the dictionary he formulated are being examined today as the first practical product of lingua sacra—the first and purest language God was said to have taught to Adam. While there are a few random studies on Muhyi’s select oeuvre, his overall intellectual contribution to early modern Ottoman letters and culture of Sufism remain largely unknown. In this paper, I will introduce Muhyi’s rich oeuvre focusing on his dialogues with Ibn al-Arabi’s metaphysical writings through a close textual analyis of his unpublished Ottoman Turkish manuscripts located in the National Library and Archives of Egypt (Dar al-Kutub, Bab al-Khalq branch) in Cairo. In doing so, I hope not only to introduce a previously overlooked prolific Sufi writer, but also to contextualize Muhyi and his intellectual world within the wider context of 16th century Ottoman socio-cultural history and Sufism studies.