ENAt the beginning of the paper the author points to the fact that Piotr Skarga wrote the life of St Casimir several years after the canonisation celebrations, which were held in Vilnius in 1604, and included it in the last edition of "Lives of the Saints" published in his lifetime (1610). St Casimir’s life was addressed by several authors, among whom was the papal legate Zaccaria Ferreri (Zacharias Ferrerius) who prepared the first description of the prince’s life for the needs of the canonisation process (1521). Yet the significance of Skarga as a propagator of St Casimir’s cult does not give rise to any doubt. This is proven by the fact that Skarga’s "Lives of the Saints" was an outstanding work, which, along with the Bible, was the most popular book in old Poland. Its various editions are being reprinted until now (the last edition appeared in 2011). The paper also emphasises the role of the Jesuits as an order of monks which from the very start made a considerable contribution to the spread of St Casimir’s cult in Lithuania. Recognising and bearing all that in mind, the author focuses on the analysis of the description of a life that Skarga included in his work, defines its hagiographic structure and the circumstances of the appearance and publishing of the work. Next he raises the problem of the relation with the sources, primarily historical ones, and defines the peculiarities of Skarga’s concept. He demonstrates how Skarga created the portrait of the holy prince and points out that three virtues were highlighted – piety (first of all Eucharistic piety), love to the neighbour, and purity. Also, Skarga extolled the saint’s purity as a heroic quality and raised it to the level of martyrdom. Thus he transcended his time and is akin to the modern individualistic approach.The paper also dwells on the attempts to define the scope of influence that Skarga’s portrait of the saint had on later centuries. This aspect is illustrated by examples of poetic texts and sermons by Mathias Casimir Sarbievius. The author resorts to a 17th-century pageant in the royal court (an oratory by Giovanni Battista Lampugnani) and Józef Andrzej Załuski’s melodrama for young people created in 1751. [From the publication]