Father Szymon Majchrowicz (1717–1783) – a Jesuit priest, writer of texts on politics and religion – was one of the missionaries active in the Polish-Lithuanian Commonwealth in the 18th century. He earned a reputation as an excellent preacher. He is also the author of a print prepared for the purposes of religious instruction, entitled The Salutary Teaching Customary at the Missions of Societas Jesu (Lviv 1767). The facsimile of the surviving work of the Jesuit missionary constitutes a valuable source not only for specialists in religious studies, for historians of culture and literature and linguists, but it is also an important document for musicologists. It comprises vernacular repertoire used in Jesuit missionary practice in the south-eastern parts of the 18th-century Polish-Lithuanian Commonwealth, where the Roman and Greek Catholic (Uniate) rites coexisted side by side.