Norman Cohn, a historian who influenced a generation of historians and social scientists with his insight that totalitarian ideologies of the 20th century, chiefly Communism and Nazism, were propelled by mythologies associated with medieval apocalyptic movements, died on July 31 in Cambridge, England. He was 92.

The cause was a degenerative heart condition, said his son, Nik Cohn.

In highly detailed, laboriously researched studies that depended on his knowledge of many ancient languages, Mr. Cohn reached far back into history to illuminate subjects of compelling current interest from totalitarianism to anti-Semitism to repression of minorities.

His gift for seeing old stories with new eyes shone in his book on the development and interpretation of the biblical story of Noah, “Noah’s Flood: The Genesis Story in Western Thought.” His crisp writing drew praise.