Bishop Cassian was born in St. Petersburg on February 29, 1892, where he graduated from the history department of the University under prof. Grevse. After the Revolution, he taught at the Orthodox Theological Institute in Petrograd. In 1922 he emigrated first to Belgrade, then to Paris, where from 1925 he became a professor at the St. Sergius Theological Institute, and from 1947, after being ordained a bishop, its rector. A prominent participant in the Russian Student Christian Movement, he became a monk in 1932 and lived on Mount Athos throughout the war. An excellent expert in ancient languages, Bishop Cassian devoted his entire life to the study of the New Testament. He was the chairman of the commission for the new translation of the Four Gospels. He died on February 4, 1965 in Paris. This book is based on a course of lectures given to students at the Orthodox Theological Institute in Paris in 1935-1936. The course contains not so much history in the proper sense, but rather guides to reading the New Testament books in the light of history.