 These topics occupy the remainder of the Politics. Books IV–VI are concerned with the existing constitutions: that is, the three deviant constitutions, as well as polity or the “mixed” constitution, which are the best attainable under most circumstances (IV.2.1289a26–38). The mixed constitution has been of special interest to scholars because it looks like a forerunner of modern republican regimes. The whole of book V investigates the causes and prevention of revolution or political change (metabolê) and civil war or faction (stasis). Books VII–VIII are devoted to the ideal constitution. As might be expected, Aristotle’s attempt to carry out this program involves many difficulties, and scholars disagree about how the two series of books (IV–VI and VII–VIII) are related to each other: for example, which were written first, which were intended to be read first, and whether they are ultimately consistent with each other. Most importantly, when Aristotle offers practical political prescriptions in Books IV–VI, is he guided by the best constitution as a regulative ideal, or is he simply abandoning political idealism and practicing  a form of Realpolitik?For a further discussion of this topic, see the following supplementary document: