Edvars and risalahs about the music theory are significant sources of musicology studies. The principles of musicological science were applied in this article. This risale by Cemalüddin Hasan İbn Ahmed has not been studied as far as is known. After the introduction and identifying the methodology, internal and external presentation of the work, the life of the author, the period of the work, sources of the risalah, the philosophy of music, the information about the theory of music are presented in a systemic way. The charts were used for the subject of similarities and differences with the 15th-century sources. Afterward, the topics related to the origin, importance, and effect of music were treated and the article was ended with the conclusion part and the Turkish translation of risalah. As explained in the article, this work which was estimated to be written in the second half of the 14th century is one of the sources of music history that contributed to the musical thought of its own era.