This study seeks to rectify some of the prevailing misconceptions about the nature of John Barth' s fiction by offering a comprehensive analysis of his fourth novel, Giles Goat-Boy (1966). The study delineates two dialectics that together create the paradoxical tensions of Barth's work. The first operates between metaphor, which seeks and affirms patterns in language, and irony, which invokes metaphor in order to deny its validity; the second operates within metaphor, between metafiction, which self-reflexively examines language and fiction, and metaphysics, which focuses attention on man and his universe. Contrary to established critical opinion on Barth, which tends to stress the role played by irony in his work, this study argues that Barth seeks to operate as freely as possible within the possibilities of metaphor for narrative pleasure and tentative truth, while still maintaining the skeptical perspective of irony. Thus the study analyzes four narrative levels in Barth's novel along the metaphorical dialectic (from metafiction to metaphysics): parodic language as style, contemporary American history as setting, the hero myth as story, and allegorical philosophy as theme (plot, character, idea). The vision of the novel, the study suggests, must be seen in a holistic perception of these dialectics and their paradoxical confrontations.