The recent book of Angeliki DELIKARI (D.) devoted to the life and the religious activity of St. Gregory the Sinaite is a fine example of a profound knowledge of the problems that such kind of study always implies. It is also a good illustration of what a perfect command of both mediaeval Greek and Slavonic can render as a scholarly result. One should acknowledge that, except for the works of A.-E. TACHIAOS, D. GONIS and K. PAVLIKIANOV, such Greek-Slavic philological studies, which also combine features of historical and archaeological analysis, were extremely rare until now.