Primary sourceBook44 BC

De Officiis

Cicero · 44 BC

Cicero's ethical treatise, written months after Caesar's assassination, repeatedly condemns Caesar as a tyrant whose ambition destroyed the Republic.

Written soon after Caesar's death, this treatise repeatedly brands Caesar a tyrant, revealing how his opponents justified the assassination.

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Open manuscript leaf with illuminated Latin text. A decorated initial at left contains a small painted portrait of a bearded man wearing a crown. Ornamental borders in gold, blue, pink, and green frame the page, with cherubs at the bottom. The Latin text is written in brown ink in a formal script. — Manuscript leaf of Cicero's De Officiis, with illuminated initial and border.

About this source

What it is

De Officiis (On Duties) is a philosophical treatise written by Cicero in October-November 44 BC, in the form of a letter to his son. It discusses honourable behaviour, personal advantage, and what to do when the two seem to conflict.

Why it matters

Written in the months after Caesar's assassination, the work criticises the recently overthrown dictator in several places, calling his rule a corruption of the Republic's political rights. It shows how one of Rome's leading statesmen justified the killing of Caesar on moral grounds, and became hugely influential later, read by Church Fathers like Augustine and Jerome.

Look closer

Why might Cicero's criticism of Caesar be sharper here than in works written during Caesar's lifetime?
What does Cicero's choice to address his son suggest about who he wanted to shape?
How might a work written just after a political killing be biased in its judgement of the person killed?

This book is part of the curated material that grounds the AI version of Julius Caesar and Cicero on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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Engraving of a standing male figure in Roman armor with a draped cloak over one shoulder, a pleated leather-style skirt with decorative lappets, and sandals, resting on a plinth. His right arm is extended outward, left hand holds a small object. The caption below reads Julius Cesar. Monochrome line hatching on a striped background.

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