1. Plato, , Books V–VII; Statesman, 291c–303d
2. Aristotle, , Books III–IV
3. Aquinas, , I–II, Q. 105, Art. 1
4. Machiavelli, , Book I
5. Montesquieu, , Books II–III, V, VIII
6. Rousseau, , Book III, Chapters 5–6
7. Hamilton & Madison, , Nos. 10, 35, 57, 62
8. Tocqueville, , Volume I, Part I; Volume II, Part III
9. Mill, , Chapters V–VIII