A small work On being and essence entered the discussion of that time on the concept of being, represented by Aristotle’s works (the Philosopher) and his Arabic interpreters Avicenna and Averroes (the Commentator). Thomas follows the Aristotelian realistic understanding of reality, but, as for its explanation, he signalizes a new understanding of being. It is clearly his own philosophical way, which enables him to enter independently into the conflict between the Augustinians and Averroists, i.e. against both sides. Thomas Aquinas’ conception of being helps to read and understand his further philosophical works more profoundly. It is the metaphysics, which from the philosophical perspective becomes a philosophical basis of the interpretation of the real world (natural and revealed) as well as a starting point for the study of the Thomas’ thinking as a whole.