The historic figure of the prominent ecclesiastical figure of the princely Rus-Ukraine, the associate of the ruler of the Galician principality, Yaroslav Osmomysl, Bishop Kosmi, was always in the sight of historians, religious scholars, archaeologists and art historians. True, its reading was usually done in the context of the study of the history of the origin of the Galician diocese in the middle of the 12th century. The problem of the founding of this diocese has a rather significant historiography. In (...) the middle of the nineteenth century, thanks to the search of the Lviv priest A. Petrushevich, it was possible to establish the main stages of its ancient history. In the years 1854-1860, about. A. Petrushevich published the "Galician Historical Collection", which contained his articles on the Galician Cathedral Church, its bishops and metropolitans. The history of the diocese was investigated in the second half of the nineteenth century. Yu Peles, M. Tikhomirov and I. Rudovich. Important pages about her past were supplemented in the twentieth century. historians M. Hrushevsky, I. Nazarko, K. Panas, S.Mudry, Yu.Fedorov, Z. Fedunkov, religious scholars - S.Kyyak and I.Skochilas, archaeologists Y.Pasternak, V.Petegirich, Yu.Lukomsky, art historians Pelensky, M. Figol, V. Vuytsik. During this time, a whole body of research has been created, which is dedicated to the study of the imprint of the Galician bishop Cosmi. He is represented by the scientific works of M. Hrushevsky, P. Gaydukov, Y.Pasternak, R.Michailova, V. Yanin. (shrink)