Essay: Considerations on the Causes of the Greatness of the Romans and their Decline

Overview
Charles de Secondat, Baron de Montesquieu published Considerations on the Causes of the Greatness of the Romans and their Decline in 1734 as a concise, searching inquiry into why Rome rose to unrivaled power and why that power ultimately unraveled. The essay sketches a series of interconnected causes rather than a single explanation, moving between political institutions, social habits, military arrangements, economic structures, and moral and religious life. Montesquieu reads Roman history as a laboratory for understanding how states maintain strength and how they decay.

Central thesis
Montesquieu's core claim is that the durability of a state rests on a balance of virtues, institutions, and material conditions; when that balance shifts toward luxury, corruption, or institutional sclerosis, decline follows. Greatness springs from civic virtue, public-spiritedness, and institutions that harness popular energy while restraining abuses of power. Decline begins when private interest displaces public spirit, when manners soften under luxury, and when institutions can no longer adapt to changing circumstances.

Military organization and civic virtue
Military factors occupy a prominent place: Rome's early success depended on citizen-soldiers motivated by honor, duty, and a sense of common cause. Such armies fostered discipline and a direct bond between civic life and military service. Montesquieu argues that the shift toward professional or mercenary forces weakened that bond, producing troops loyal to pay rather than to the state and eroding the civic virtues that sustained republican institutions.

Institutions, law, and governance
Stable institutions and mixed constitutions help explain Rome's expansion and governance, but institutions can ossify or be subverted by concentration of power. Montesquieu highlights how Rome's republican structures, its magistracies, legal frameworks, and checks on authority, created effective mechanisms for collective action. Over time, however, accumulation of power in fewer hands, erosion of legal norms, and institutional adaptation to imperial scale undermined accountability and invited despotism.

Economy, slavery, and social change
Economic developments played a dual role: conquest and integration of territories brought wealth that financed further expansion, but vast riches and the prevalence of slave labor altered social relations and economic incentives. Montesquieu sees slavery and the resulting complacency among free citizens as corrosive, reducing industriousness and fostering dependence on consumption rather than production. Growing inequality and a taste for luxury reshaped priorities away from public service and toward private display.

Moral and religious dimensions
Manners and religion are treated as decisive. Montesquieu contends that shifts in moral sentiment, softening of austerity, loss of austerely public ethics, and conversion to beliefs that discourage martial virtues, affected Rome's capacity for collective self-defense. He links the spread of luxury and the decline of traditional Roman virtues to changes in family life, public customs, and religious attitudes, suggesting that spiritual and cultural transformations have political consequences.

Implications and legacy
The essay functions as both historical diagnosis and prudential warning: longevity depends on cultivating civic virtue, designing resilient institutions, and attending to economic and moral balance. Montesquieu's reflections anticipate later arguments about republicanism, corruption, and the social foundations of power, influencing Enlightenment and modern debates about how law, custom, and governance interact. The work invites readers to consider how present arrangements might sow either strength or decay, so that the lessons of Rome inform policies for prevention of decline.