Historians have long debated the extent to which the secret network of Freemasonry was a main factor in the Enlightenment. The leaders of the Enlightenment included Freemasons such as Diderot, Montesquieu, Voltaire, Pope, Horace Walpole, Sir Robert Walpole, Mozart, Goethe, Frederick the Great, Benjamin Franklin, and George Washington. Norman Davies said that Freemasonry was a powerful force on behalf of Liberalism in Europe, from about 1700 to the twentieth century. It expanded rapidly during the Age of Enlightenment, reaching practically every country in Europe. It was especially attractive to powerful aristocrats and politicians as well as intellectuals, artists and political activists.