The volume explores the unpublished work of the Greek Orthodox Patriarch Kyrillos Loukaris (c.1570–1638), specifically focusing on his sermons delivered between 1602 and 1626. The study centers on Loukaris’ extant sermons, preserved in an autograph manuscript corpus titled Didachae, currently housed in the collection of the Metochion of the Holy Sepulchre. Following a comprehensive codicological and paleographical examination and the compilation of an annotated inventory of the material, the volume delves into various scholarly inquiries. These include identifying the official corpus of Loukaris’ homiletic work, defining criteria for the standard form, structure, subject matter, and language of the sermons, and analyzing the numerous references to the preacher's diverse readings, including both Orthodox and Latin sources. Moreover, the inventory encompasses all entries found in the codices, presenting the internal classification of the sermons, their methodologies, arguments, the development of each topic, and the application of systems for subsequent processing and revision of the material. Consequently, the description of Loukaris’ unpublished Didachae, regarded as his magnum opus, significantly enriches the modern bibliography on the Patriarch and contributes to the growing field of Eastern Christian homiletics in the early modern period.