'The one-eyed man' asks what value literary sources may have for the social historian, who is accustomed to work with factual evidence. After a survey of the possible approaches and the work of previous scholars such as Kohn-Bramstedt and Auerbach, the author argues that the social novel, based on the novelist's observation and written to propagate his views, can aid historical knowledge particularly in the fields of mentality and the everyday. Studies of eighteen novels which deal with German life between 1848 and 1968 support and develop this thesis. Some novelists are concerned to propagate controversial philosophical or political views, some use peculiar theories of society to structure their work, yet there is still reason to assume that a writer of high literary quality will present details of everyday life fairly. Novels both are historical evidence in themselves, as showing an intelligent contemporary's opinions, and provide historical evidence in the mentalities and lifestyles depicted. Only writers who have a Utopian aim, or who are subject to interference from some kind of censorship, form an exception. The scholar's sensitivity is required to determine whether a particular novel gives good evidence or not.