This is a study of foreign affairs, which questions their place in the grand scheme of civilization, and asks whether defences against the invasion of strangers influence the evolution of culture. The author seeks to show that diplomacy, intelligence, defence and warfare, intervention and law, and trade and aid should interact and form a whole pattern, essential if nations are to move safely into the 21st century. Examining the human experience, the text documents fear of the foreigner as a visceral response so pervasive that it transcends human memory, individual experience, and even logical analysis. It aims to show that the tension created by having to live as neighbours with those who are perceived as irredeemably alien has been one of the major causes of the rise of civilizations.