Decisive changes in the history of rhetoric occurred with the publication of Francis Bacon's "Advancement of Learning" and "De augmentis scientiarum" and "Leviathan" by Thomas Hobbes. Bacon and Hobbes responded to the problem of eloquence common to scientists in the early seventeenth century, which centered on three major philosophical-rhetorical concerns: an interest in the persuasive as opposed to the communicative aspects of rhetoric, an interest in faculty psychology, and the interpretation of method. Although Bacon and Hobbes addressed similar concerns, their treatments differ in the following ways: Hobbes favored the recording and teaching functions of scientific communication to the persuasive aspects; Hobbes, in his interpretation of faculty psychology shifted the emphasis from audience centered to speaker/writer centered rhetoric; and Bacon viewed rhetorical method as persuasion following scientific innovation, while Hobbes regarded rhetorical method as scientific invention and demonstration. The problems of the rhetorical dimensions of science and especially of the roles of speaker or writer became lost in the physical sciences after Newton but have reappeared in the twentieth century's interest in the rhetorically concerned history and philosophy of science. (Author/DF)