Examines the teaching and practice of the twin arts of argumentation -- rhetoric and dialectic -- in the time of Galileo. Galileo was an ardent controversialist on behalf of his astronomical theories, yet many today are unacquainted with the kinds of argument that became a focal point in his famous trial. The authors combine their vast knowledge of rhetoric, history, and philosophy to explain the background of the dispute between science and religion. They present an engaging discussion of the prevailing modes of rhetorical and scientific arguments in Northern Italy during the Renaissance. They display primary texts on the arts of rhetoric and dialectic by authors whose thought was known to Galileo.