No student of economic developments in Russia could fail to be impressed by the profound influence exercised over the developments by theories and ideas concerning them. Two periods are to be distinguished in the development of sociological thought. The first, which may be termed the period of Utopian agrarianism, occupied the period between the Emancipation of the serfs and the '90's of last century. The second period of sociological thought, lasting from '90's to the outbreak of the Great War, showed a transition to Marxism and industrial Socialism. The right wing, headed by Peter Struve, abandoned the Marxian doctrine of revolutionary progress, and adopted the evolutionary point of view. They held that the transition to the Socialist State could best be effected by the slow and peaceful methods of constitutional reform. The first and second Dumas are sharply distinguished from the later Assemblies. They met between 1905 and 1907, which has been described as "heroic age" of the Russian Duma.