Treatise De Consideratione ad Eugenium Papam III. is not in general public awareness of the power known. Nevertheless, his message on the theme of the papacy and practical guides to the character of the Pope is still valid. This thesis aims to familiarize with the life of the author of the letter, and Bernard of Clairvaux to outline the time and circumstances of the letter, as well as with the personality of Pope Eugene III. to whom the letter is addressed. Treatise is divided into five books, this work deals mainly with the fourth book. In the fourth book we find a few key topics. Relates to the personality of the Pope, what would be its features and how it should behave. It is a theme of "two swords" on which Bernard shows secular and ecclesiastical power. There is here the topic of the internal layout of the Church. Keywords Bernard of Clairvaux, Eugenius III., Letter to De Consideratione, allegory "two swords", religious and secular power

This thesis examines the transmission of the idea of crusade to Poland and the subsequent Polish response to the idea of crusade in the twelfth century. It determines the key mechanisms by which the idea of crusade was transmitted to Poland and through an analysis of primary contemporary sources the thesis provides compelling evidence that the Polish elites were highly familiar with, and receptive to, the idea of crusade. Moreover, this thesis argues that the Poles were conscious participants in the crusades and undertook various crusading activities during the twelfth century. These findings are contrary to the established position in Polish historiography, and bring many sources to an English-speaking audience for the first time. / Through an examination of narrative sources this thesis demonstrates that the Polish elites were enthusiastic supporters of the idea of crusade within a decade of the First Crusade. This thesis shows that under the leadership of the Piast dynasty the Poles engaged in Christian holy war (proto-crusading): the conquest of Pomerania (1102–1128), contributed armies to three theatres of the Second Crusade (1147–1148), and launched major expeditions against the Prussian apostates (1166 and 1192). / This thesis identifies the influence of the idea of crusade on the actions of the Piasts and in particular, Boleslaw III’s sons (the Piast Juniors), and the importance of family traditions. The thesis presents new propositions in regards to the crusades in Prussia and key Polish crusader participants: the involvement of the Polish crusader army under the command of Mieszko III in the Wendish Crusade (July–August 1147); previously unreported in English historiography, the first known example of crusading in Prussia led by Boleslaw IV (November–December 1147); and Henry of Sandomierz’s leadership of the Polish crusader contingent to the Holy Land (1147–1148).