Yes, Ellen, but my quote (pseudo quote?) refers not just to traitors from within. When I first heard it the person who said it referred to Jews and Arabs whose cultures have a lot of parallel history, way back in time. You could say it also about Jews and Christians with the Old Testament of the Bible referring to Jewish society. Also, my memories of sitting around at Uni with a bunch of social lefties and the Trotskyists arguing with the Socialists arguing with the Communists etc etc ad infinitum. They wouldn't argue so long and hard with the Liberals (who are the conservative party here) because they would assume that the divide was too deep to try to argue or convince or persuade.

Helen