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.

This thesis is engaged in the theme of natural law, especially in sources of natural law - in theories, which are labelled as "classic". The thesis focuses on these theories (Aristotle, stoicism, Thomas Aquinas) and their common points, which are proper to these theories. That is the object of this thesis. These points present the essence of natural law. The first part explains problem of the term "natural law". The second part deals with the classic theories. The third chapter summarises findings of the second part. The fourth part is devoted to the similarity between the classic theories and the modern (enlightenment) theories. This chapter is devoted to the connection between natural law and positive law too.

Medieval philosophy in the Arabic world has sought to harmonize the Greek philosophic tradition with the Islamic religion. Many rulers, scholars and theologians were against this intellectual approach and defend the Islam from the philosophers. The position of philosophy and its followers in the Arabic realm was therefore uneasy. Many scholars had to hide their opinions between the lines and avoid to doing philosophy publicly. Alongside the unfriendly environment, the position of philosophy in the Arabic society was also determined by common notion of scholars, that the revealing of the philosophical thoughts can be harmful for uneducated citizen, as well as influenced by mysticism. The aim of this thesis is to summarize the main philosophical approaches responding to the problematic position of philosophy in the Arabic world. Crucial will be the philosophy of solitary by Ibn Bajja, where the author seeks to bond tight the philosopher's life with the city and thus present a new role of philosopher in the Arabic society. Keywords Ibn Bajja, Rule of the Solitary, Al-Farabi, Political Regime, Aristotle, Nicomachean Ethics, Plato, The Republic, political philosophy, mysticism, ethics, philosopher, virtue, city, weeds, knowledge, governance, happiness