The Spirit of the Laws by {author}: summary and why it matters

What it argues

Montesquieu studies how laws relate to the nature of each government, to climate, geography, commerce and religion. He distinguishes republics, monarchies and despotisms, assigning each a guiding principle: virtue, honor and fear.

The part with the greatest influence is his account of political liberty. Liberty, he says, exists only where power is not abused, and power stops power only when the legislative, executive and judicial functions are kept apart and able to check one another. He praises the English constitution as an example, though readers still debate how accurately he described it.

He also writes on the evils of slavery, the benefits of commerce in softening manners, the need for moderate penalties and the importance of local circumstance.

Why it matters

The Federalist cites Montesquieu as the oracle on separation of powers, and the idea of checks and balances in the American Constitution is inconceivable without him. Conservatives return to him when arguing against concentrated power, whether in an imperial presidency or an administrative state that combines lawmaking, enforcement and adjudication.

About the author

Charles-Louis de Secondat, Baron de Montesquieu (1689-1755) was a French nobleman and magistrate from near Bordeaux who first became known for the Persian Letters, a satirical novel. He spent about two decades on The Spirit of the Laws, traveling in Europe and spending a year in England, and the book was placed on the Catholic Church's Index of Prohibited Books in 1751.

Who should read it

Readers of the founding and constitutional design; select the books on liberty and the constitution rather than trying to read the whole.