The essays called Cato's Letters were written by two Englishmen, concealing their identities with the honored ancient Roman name of Cato. Later their identities were revealed as John Trenchard and Thomas Gordon. Their 144 essays were published from 1720 to 1723, originally in the London Journal, later in the British Journal. These newspaper essays condemning tyranny and advancing principles of freedom of conscience and freedom of speech, were a main vehicle for spreading the concepts that had been developed by John Locke. The Letters were collected and printed as Essays on Liberty, Civil and Religious. A measure of their influence is attested by six editions printed by 1755. A generation later their arguments immensely influenced American colonists, where it is estimated that half the private libraries in the American Colonies held bound volumes of Cato's Letters on their shelves.
The prototypical 'Cato' was Cato the Younger (95–46 BCE), the implacable foe of Julius Caesar and a famously stubborn champion of republican principles.
The think tank, the Cato Institute founded in 1977 in Washington, D.C., takes its name from Cato's Letters.
