Summary This article shows how Coleridge's “The Rime of the Ancient Mariner” engages the reader in something akin to a dialectic process of making sense of the mariner's seascape. Analysis reveals that the poem does this by constantly confronting the reader within the same image with familiar and unfamiliar phenomena that she/he has to synthesise into a meaningful whole. The meaningful whole that comes into being as a result of the synthesis of opposites, suggests the idea that the whole is, as Coleridge put it, “grander” and “vaster” than we can comprehend, an idea that Coleridge advocated in several of his nonpoetic writings. Very specifically, the anti-thetical presence of familiarity and unfamiliarity creates confusion about the realm's visible features, until the imagination eliminates this confusion by synthesising the underlying antitheses. This argument is contextualised firstly (and briefly) against the background of the history of the idea of the dialectic, or the synthesis of opposites, and especially its development in German transcendental thought, and secondly, against aspects of Coleridge's own ars poetica, which was greatly influenced by German transcendental thought. Coleridge's indebtedness to the German thinkers of the time is the subject of much scholarly work. “The Rime of the Ancient Mariner”, however, predates most of the important idealist writings. The article points out parallels between the composition of Coleridge's images in “The Rime of the Ancient Mariner” and the underpinnings of German transcendental thought. These parallels could indicate that Coleridge was influenced by early idealist writing or that he did indeed – as he claimed – think simultaneously and independently the same thoughts as the important German idealist thinkers of his time. Either way, the parallels indicate a Zeitgeist so strong that it found expression also in Coleridge's poetic output.