Research on manuscripts preserved in Turkish museums and libraries have extanded our knowledge of bibliophiles in the states eatablished in Anatolia between the 12th and 14th centuries, and subsequently in the Ottoman Empire, where Ottoman sultans and statesmen collected artistic manuscripts. One Ottoman bibliophile was Haci Selim Aga, a statesman and member of the elite in the first half of the 18th century who was adopted son of the reisulkuttap (the head of court scribes) Mustafa Efendi. The latter's biological son, Asir Efendi, commissioned an elegant library building followinghis father's last wishes, and his grandson Hafid Efendi was also a bibliophile. Haci Selim Aga, founded a library in the district of Uskudar and endowed it with his collection of books, which included illuminated manuscripts. One of these was a copy of Mavlana Jalal al-Din Rumi's Mathnavi, dating from 1386. The design of the manuscript's illumination has been the subject of a master's thesis; the manuscript's life story, which has so far not been researched, is the focus of this paper. A seal impression and an annotation revealed in the course of the latest repairs to the manuscript were important findings that shed new light on its life story. Colophons in manuscripts provide evidence of other works by the same calligrapher. Although the identities of the first owner and their heirs are not completely clear from these findings, annotations on the first and last leaves of a manuscript owned by a descendant have offered valuable clues about the family. Upon reexamining the illumination of the Mathnavi in question, which was the work of a master artist, it became evident that other artists also emulatedhis style, which continued to be influential into the early 15th century. This book, belonging to Haci Selim Aga, and other books discussed in the article have made significant contributions to our knowledge of book collecting among cultured intellectuals during the late 14th and early 15th centuries.