One of the most important interests of Herman Melville was the discovery of truth and the issue of its representation. This dissertation attempts to read Moby-Dick as a novel that embodies Melville's discovery of truth and its issue of representation. As it is well known, Moby-Dick is an experiment of several different formats and a mix that includes the travelogue, the sermon, the tragedy, and the epic. The heterogeneous experiment and mix of such formats seem to be inevitable in a novel like Moby-Dick, which deals with the discovery of unobtainable truth and the issue of its representation, and this may even be regarded as the result of the author's great efforts. One of the aspects that distinguished Moby-Dick from the existing traditional novel format was the side branch stories including the “Cetology” chapter. By going beyond the level of defending or justifying the formal characteristics of the cetological chapters, this dissertation attempts to apply analysis focusing on how these cetological chapters actually add thematic meaning to Moby-Dick, what role they play, and what effect they possess. In short, the side branch stories do not stop at being simply digressions that suggest ancillary narration or introduction of the subject matter of whales and whaling from both the aspects of quantity as well as content, but also are considered important parts that endow pursuit of truth and the meaning of representation to the main story of the tracking of the whale. Therefore, this dissertation, by analyzing in detail the side branch stories including Chapter 32 “Cetology,” looks into the role of these chapters,especially, what role these chapters perform in relation to the inquiry into truth and its representation. The first chapter of the main body of this dissertation looks into how the cetological chapters emphasize the difficulty of grasping the truth of the whale, and by extension, the search for truth and the difficulty of its representation. The difficulty of grasping the truth of the whale interflows with the sublimity of the whale, which emphasizes this sublimity with the obscurity of the search for truth. The second chapter of the main body attempts to examine how the cetological chapters imply the attitude whalers/artists must adopt in pursuing and searching for the whale/truth. This, in other words,involves suggesting the limits of scientific methodology and implies the courage to directly see, feel and ‘experience’ the ‘living’ whale. Lastly, the final third chapter of the main body attempts to examine how the cetological chapters emphasize the importance of the ‘relativity’ of truth, and ‘the interpretive act’ of truth itself, which is realized by Ishmael in the process of his search for truth. This is clearly revealed through the comparison between Ahab and Ishmael.