The functionality of illustrative diagrams and their scholarly importance in representing cosmological ideas has been discussed in the context of Islamic(ate) cosmographical diagrams by Ahmet Karamustafa in the multi-volume History of Cartography. Karamustafa argued that in Islam there had been a lack of a continuous tradition of cosmological speculation that developed diagrams illustrating major features of a universally accepted Islamic cosmology. While this assessment holds true, early modern Ottoman Sufi poets/authors—in particular, members of the Khalwatiyya and its offshoots—and their literature surprise us with an unexpected phenomenon: narratives with complex circular diagrams, letters, and numbers with esoteric content. Tentatively calling them “mystical cosmologies”, in this presentation I will focus on the uses and functions of “the circle” surfacing as the geometric form of choice to communicate philosophical, scientific, mystical, Qur’anic/Prophetic, and esoteric content in 16th century Ottoman Sufi manuscripts. My preliminary research indicates that Ottoman Sufis drew diagrams to depict a knowledge that combined “science”, as in the scientific study of letters and numerology, with that of Islamic mysticism (tasawwuf), as in the study of the Divine and “the sacred”. Relying only in part on Ibn al-Arabi’s influence, this eclectic methodology aimed to reach a harmonious understanding of the mechanics of the Universe—one that combined the sacred and the scientific strands of knowledge-to grasp God’s Universe and mankind’s role in the cosmos. These Sufi authors prioritized drawing circular diagrams to prove their points: a novel and unstudied phenomenon, which we do not see in the mainstream Islamic religious literature of the period produced in the Ottoman domains. As an Ottoman historian and Sufism scholar, I am approaching this previously unknown phenomenon as a “new type of knowledge in the Ottoman World”. What advances toward a “universal learning” did these authors assert through the use of these innovative visual elements? Why did they draw circles to depict their visions and experiences? Investigating the mystical and visual cosmologies and their textual contexts, I hope to explore new formations of knowledge in the early modern Ottoman world, one which harmonized Neo-Platonic and Aristotelian “scientific” knowledge with Islamic mysticism, and Qur’anic teachings prioritizing the geometric form of the “circle” at its core.