In the 1830s, the frenchman alexis de tocqueville wrote that the "principle of " was nowhere more evident than in america.

Alexis de Tocqueville was a French diplomat. His work "Democracy in America" appeared in 1835. Tocqueville wrote about the principle of equality and used the phrase "equality of conditions".
He wrote that the "principle of equality" was nowhere more evident than in America.

The answer is democracy. In 1831, Alexis de Tocqueville was sent to America by the French government with Gustave de Beaumont to study the American prison system, but he later admitted it was a ruse to study American society instead.