Virtue is one of the most important concepts in Spinoza’s ethical theory. His understanding of virtue is informed by the received meaning of the Latin virtus, which has two main definitions. First, the literal meaning of the word is manliness or manhood. As such, virtus refers to what were traditionally conceived as positive masculine traits, such as strength, power, daring, courage. Second, virtus is the traditional Latin rendering of the Greek philosophical term arete, which refers primarily to the moral excellence that consists of dispositions or habits to think, feel, and act in morally good ways. Thus, virtue is ambiguous in referring, on one hand, to strength and, on the other, to moral excellence. These two meanings can be complementary, as moral excellence is often conceived as the realization of a human being’s essential powers, which means that moral excellence connotes a kind of power or strength. However, “virtue” does not necessarily imply both strength and moral excellence. For example, in describing the virtue of princes, Machiavelli construed virtù (the Italian of virtus) primarily as strength or power.