In the modern world, material is only wealth if you can get rid of it. The British miner cannot eat his coal, nor clothe his children with it, nor build his house with it. If coal is to mean for the British miner food and shelter and clothing, he must get rid of it. Get rid of it, that is, to someone who has money, sell it. But how is that someone to get money? He can only get it by one means: By getting rid of his material to someone who has money, who can only get money by getting rid of his material round the world.