Nobody today maintains that Spinoza is not an original philosopher. Nevertheless, Harry Austryn Wolfson (1958)—that extremely learned historian of ideas—set himself the task of finding out which sources Spinoza used, or may have used, in formulating each detail of his main work, the Ethics. With extraordinary success, Wolfson traced influences on Spinoza’s formulations. One task of argumentation analysis is to transfer the historian’s results, which are formulated in terms of influences, into a rich set of patterns of argumentation. This is a task of hypothetical reconstruction. It clarifies the cognitive content of a historical text by pointing out contrasts and by explicating agreements and disagreements. It rejects the existence of sovereign pronouncements made in a kind of communicational vacuum.