Men fight hardest when they feel that the foe is at once an old enemy and an eternal stranger. Men can think of this difference even at the point of death; for it is a difference about the meaning of life. Men are moved in these things by something far higher and holier than policy; by hatred. There is a religious war when two worlds meet; that is when two visions of the world meet; or in more modern language when two moral atmospheres meet. What is the one man's breath is the other man's poison; and it is vain to talk of giving a pestilence a place in the sun. And this is what we must understand, even at the expense of digression, if we would see what really happened in the Mediterranean; when right athwart the rising of the Republic on the Tiber, a thing overtopping and disdaining it, dark with all the riddles of Asia and trailing all the tribes and dependencies of imperialism, came Carthage riding on the sea. —G K Chesterton