As with On the Origin of Species, we find that the work to be considered here-The Structure and Distribution of Coral Reefs-demonstrates Darwin's use of hedges to project the ethos of a cautious scientist. Hedges are linguistic elements such as perhaps, might, to a certain degree, or it is possible that. When people use hedges, they signal that they are taking a cautious stance on the truth-value of the referential matter they seek to convey. Hedges are a type of metadiscourse, a level of writing in which authors draw attention to the very art of writing itself-they discourse about their discourse (Crismore, Talking to Readers). This metadiscursive trait, however, represents only one aspect of Darwin's rhetoric. In Coral Reefs, he sculpts a key chapter into a Ciceronian form so pure that one might have to return to the Renaissance to find a parallel, and within this larger form, he strategically places hedges and other metadiscourse. He, further, employs visuals (drawings, diagrams, and maps) for persuasion at those points were the tension between his audiences preconceptions and the new theory being presented threatens to reach a dangerous level. The visuals and the metadiscursive commentary about them, also, help to establish his ethos and to build the argument for his theory of coral reefs. These elements, so perfectly embodied in Coral Reefs, were the rhetorical tools of an extremely sophisticated scientific mind which has much to pass down to our own conception of scientific writing. All too many of today's professional, academic, and textbook writers view exposition of findings as being all that is needed-and other parts of the written document, including visuals, can be handled even more perfunctorily: facts by themselves are enough, after all, according to this view. Darwin, however, believed that bald facts and blunt explanations were insufficient, as he clearly indicates in his A utobiography. There, he writes that in Origin he had first presented a short and rather vague discussion of his own innovative idea in the area of embryology. Later, other scientists got the for the new idea. Darwin felt no bitterness, for he knew that the fault had been his alone and that this fault was a rhetorical one: I failed to impress my readers; and he who succeeds in doing so deserves, in my opinion, all the credit (Barlow 125). Facts and blunt explanations were not enough-rhetorical strategies were needed to impress the reader-even (and we have some reason to say especially) professional scientists. Since, even granting the A utobiography, there will always remain a question about the precise nature of the intended audience for Origin, and since, moreover, a cloud of non-scientific, anachronistic controversy hangs over its theory of natural selection, we have turned to Darwin's work on coral reefs: this work was unquestionably intended for the professional scientists, and yet it also, like Origin, sets forth a theory that involves a historical development measured in geological time. Coral Reefs has, we think, some