Barnett later said: "I can safely say there were only two books that I read at Oxford which strongly influenced my subsequent approach – one part of the Special Subject, and the other something which a friend recommended to me. The first was Clausewitz's "On War", which was part of a Special Subject on military history and the theory of war. The other was Lewis Mumford's "Technics and Civilization" – if I read it again now I do not know what I would think of it, but certainly that was a starting point for my interest in looking at history in technological terms rather than in the constitutional/political terms prevalent at Oxford".