This paper aims to explore how the main character Stephen talks with the world through the ‘interior monologue’ based on the Jewish German philosopher Martin Buber’s ‘dialogic philosophy and aesthetics,’ and attempt a new approach to the analysis of the work. Buber’s theory of dialogic aesthetics is significant in the interpretation of “Proteus” because, in this episode concerning the symbolic fight between history and art, Stephen clearly shows his vision of the ‘eternal priest of art,’ which he regards as the ‘eternal You,’ in Buber’s terms, being worth substituting for the suggestion of the holy calling of priest in A Portrait of a Young Artist as a Young Man. Throughout Ulysses, this episode is characterized as a ‘threshold episode’ that connects Stephen’s world and Bloom’s world, and the main character realizes the importance of finding art through the dialogues with various ‘yous’ that he meets with his body one by one in many ‘I―It’ relationships.