The Discourses and The Prince were written in the same years out of the same reading of Livy, and Machiavelli refers in The Prince to having discussed republics elsewhere at length. They are usually read as a pair that disagrees: the Discourses argues that a republic with contesting classes is more durable than a principality, while The Prince advises a single ruler on holding a state. Reading either alone produces the caricature. The method is identical in both, which is to derive rules from what Roman and contemporary rulers actually did rather than from what they should have done.