ENThe article presents widely comprehended intellectual culture in the Grand Duchy of Lithuania during the seventeenth century and discusses transformations in ideology, literature, science, the school system, libraries and readership which affected not solely the producers but also the recipients. The examined processes took place from ca 1520 to 1660. The reception of the new civilizational accomplishments in the Grand Duchy of Lithuania ran its course much more rapid than in the Crown. Already at the end of the sixteenth century, the number of churches totalled ca 200, and 50 years later it rose to 360 churches and 100 monasteries and convents. In contrast to the Crown, the Counter-Reformation campaign conducted here by the Jesuits, who were especially interested in the educational system, was also much more extensive (there were 10 colleges, headed by the Vilno Academy). The dissemination of culture was testified by the growing number of men of letters, lecturers and creators of local culture. Already in the second half of the sixteenth century about 45 per cent of all authors whose works appeared in print came from the Grand Duchy; the same holds true for about 40 per cent of lecturers at the Academy in the seventeenth century. Both the Reformation and the Catholic Church used the Polish language in their contacts with the faithful. Attempts at issuing books written in Lithuanian were scarce (only 14 titles appeared in the first half of the seventeenth century). The Polish language was also employed by the Uniate Church.A rapid Polonization of the upper classes and representatives of the middle classes, bound up with close ties with the former, was also the outcome of their cultural aspirations. The Polish language, according to J. Jurginis, offered the best opportunities for the integration of a multi-national state; the inhabitants of the Western Russian terrains regarded it as a comprehensible "Slav" language. Already in 1614 the "Lithuanian Statute" was translated into Polish and published upon the basis of an edition which was printed in 1588 in the Russian alphabet. The process of Polonization was completed in 1696 when at the request of the local nobility the official language, which up to that time was Russian, was replaced by Polish. The publication of books in the Grand Duchy of Lithuania illustrates the rate of Polonization and the dissemination of culture. Although six Russian printing shops issued 13 per cent of all publications (including a primer and a grammar book), books in Polish and Latin constituted about 40 and 35 per cent of the overall output, respectively. This was also the period of the formation of the Byelorussian language ("Leksikon Slavyenorosskiy" by Pamva Berynda, 1653). A characteristic feature of a syncretic model of culture, in which the Catholic and Calvinist creed (the latter lasted longer than in the Crown), Eastern rite churches, synagogues and Muslim mosques coexisted, was the independence of the ruling class of the Duchy, strongly emphasized in Polish- language publications and correspondence. It was this factor which presented the greatest threat to the Union during the "Swedish deluge".This independence was expressed in numerous works of local authors, unpublished up to the nineteenth century, who wrote in Polish and were graduates of Jesuit, Calvinist, Lutheran and Russian schools (the diaries of Filip Obu- chowicz, Zygmunt Druszkiewicz, Stefan Medeksza, Jan Cedrowski, Bogusław Maskiewicz and others). The theologian Mikołaj Łęczycki, the historian Wojciech Wijuk Kojałowicz, the musicologist Zygmunt Lauxmin, the lawyer Jan Konstantynowicz, representatives of the exact sciences: Jan Dusiatski and Wawrzyniec Susliga, became renowned. Cultural advancement was evidenced by the growing number of not only institutional but also private libraries, including those belonging to the townspeople as well as by the emergence of provincial cultural centres - Orsza, Nieśwież, Nowogródek, Słuck, Jewie, Mohylew, Kutein, Mysz, Pińsk and Kiejdany. The culture of the Early Baroque was adversely affected by wartime devastations. In 1655 the Muscovite army led by Prince Khovansky plundered Vilno, and took away valuable objects and paintings as well as artists and craftsmen, who, according to S. Abecedarski, subsequently comprised about 10 per cent of the highly skilled masters in Moscow. During the 1670s, despite war losses, the Grand Duchy remained the scene of an active school system, expanding libraries and an increasing number of readers, especially of Polish-language publications. Three new printing shops specialized in Polish, Latin and Cyrillic books, including a printing shop in Sluck which continued the work pursued at the end of the sixteenth century by the then flourishing Church publishers. This book production, which included primarily translations from Polish, played an immense role in spreading the ideals of humanistic culture.