This theory is usually contrasted with a theory that talks about events occurring in the fullness of time, or when an overwhelming wave of smaller events causes certain developments to occur. The Great Man approach to history was most fashionable with professional historians in the 19th century; a popular work of this school is the Encyclopædia Britannica Eleventh Edition (1911) which contains lengthy and detailed biographies about the great men of history, but very few general or social histories. For example, all information on the post-Roman "Migrations Period" of European History is compiled under the biography of Attila the Hun.