 The book explored world history in terms of the effect different old world civilizations had on one another, and cites the deep influence of Western civilization on the rest of the world to argue that societal contact with foreign civilizations is the primary force in driving historical change.It had a major impact on historical theory by emphasizing cultural fusions, in contrast to Spengler's view of discrete, independent civilizations.Hugh Trevor-Roper wrote a glowing review in "The New York Times Book Review".