Cicero addresses this text to his son, Marcus, who lives in Athens and studies under Cratippus, the Peripatetic philosopher. The Peripatetics were a school of philosophers in Ancient Greece founded by Aristotle. In this text, Cicero aims to guide his son through a consideration of duty, or "appropriate action" (24) and the issues that may arise when one decides what that action might be. He explains that appropriate action can be either an "entirely," or "correct" action, or an "ordinarily," or "common" action (25). He aims to address the latter actions in this text. When one makes an ordinarily appropriate action, it is based on a decision as to whether the action will be honorable or useful, whether its utility is at odds with its honorability, and vice versa.

He defines duty as arising from one of four kinds of virtue: the recognition of truth, or wisdom;the preservation of communal, humanconnections, or justice; the power of a "lofty and unconquerable spirit," (28) or greatness; and the observation of social mores, or moderation. The first virtue concerns truth, while the other three concern what Cicero calls "necessities" (27). Necessities sustainhuman life, both physical and spiritual.

Concerning wisdom, Cicero explains that humans concern themselves with survival, like animals, but unlike animals, have awareness of the past and future, and thus use reasoning in their decision-making.