Chapter 3 engages in a close analysis of several interrelated categories of the normative order that, together, provide the ethical foundations of the res publica. They include the concepts of virtue, the common good, citizenship, education and customs, which are discussed as representing a coherent normative political theory influenced by the classical republican tradition, but also by the empirical context of the Commonwealth. For the republican writers, it was evident that in a well-ordered political community liberty could be preserved only by the law and virtue. They paid scrupulous attention to character formation and the duties of citizenship. It is argued that, in doing so, they were followers of Aristotle and civic humanists for whom the virtuous character of citizens rather than a well-designed institutional order was the most important safeguard of liberty. This chapter stresses the influence of Platonic and Aristotelian insights in the republican discourse. Numerous texts published in the sixteenth century shared the same conclusion, that a free political community needed constant attention and improvement, because of the weakness of imperfect human nature