Thesis will be focused on multilayered ideal of sobriety and closer examination of its meanings in the text of the Encyclical Laudato si'. The analytical part of the thesis will examine the term sobriety (sobrietas), its occurrence in texts of the Old and New Testament and the context of its use as a cardinal virtue or moderate political action. The Encyclical Laudato si' by Pope Francis will also be presented. The second part will deal with ethical aspects of sobriety in relation to the environment, to oneself, to the other person and to God in the footsteps of Pope in the Encyclical. Keywords sobriety, virtue ethics, moderate politics, alternative lifestyle, Encyclical Laudato si', Pope Francis, socio-ecological crisis

The thesis focuses on Aristotelian-Thomist ethics system. In mainly deals with the differences in concept of beatitude, good and related issues, like the science of virtues. The emphasis is placed on understanding and covering the differences in aproach of St. Thomas Aquinas and Aristotele to these ethical topics. Firs the thesis characterises the main issue in Nicomachean Ethics, then outlines the thoughts and ideas of St. Thomas Aquinas in his Commentary, with emphasis on its diference from Aristoteles teachings. First three chapters are therefore the more descriptive part of the thesis, which is based on both primary and secondary textual sources. The fourth chapter is, then, the crucial, practical part, that summarizes St. Thomas theses and ideas concerning beatitude, good and happiness, coming from his unrivaled Commentary on the Ethics.