Educated partly in Edinburgh Constant was a long-time intimate of Madame de Stael. He consistently opposed political extremism and despotism. In opposition to Rousseau he contrasted the ‘liberty of the ancients’ in the collective life of the polity, with the ‘liberty of the moderns’, or the individualistic liberty of individuals in modern commercial and market-dominated society. He was a founding figure of modern liberal theory. Principal writings include Principes de politique (1810), and a multi-volume history of religion, De la religion (1824–31).