races, forget the fact, which is obvious when it has once been pointed out, that the progressive nations are those which happen to have valuable coal fields.  Countries which have no coal are obliged to import it paying the freight, or to smelt their iron with charcoal This process makes excellent steel—­the superiority of Swedish razors is due to wood-smelting—­but it is so wasteful of wood that the Mediterranean peoples very early in history injured their climate by cutting down their scanty forests, thereby diminishing their rainfall, and allowing the soil to be washed off the hillsides.  The coasts of the Mediterranean are, in consequence, far less productive than they were two thousand years ago.  But in England, when the start was once made, all circumstances conspired to turn our once beautiful island into a chaos of factories and mean streets, reeking of smoke, millionaires, and paupers.  We were no longer able to grow our own food; but we made masses of goods which the manufacturers ware eager to exchange for it; and the population grew like crops on a newly-irrigated desert.  During the nineteenth century the numbers were nearly quadrupled.  Let those who think that the population of a country can be increased at will, reflect whether it is likely that any physical, moral, or psychological change came over the nation coincidently with the inventions of the spinning-jenny and the steam-engine.  It is too obvious for dispute that it was the possession of capital wanting employment, and of natural advantages for using it, that called these multitudes of human beings into existence, to eat the food which they paid for by their labour.  And it should be equally obvious that the existence of forty-six millions of people upon 121,000 square miles of territory depends entirely upon our finding a market for our manufactures abroad, for so only are we able to pay for the food of the people.  It is most unfortunate that these exports must, with our present population, include coal, which, if we had any thought for posterity, we should guard jealously and use sparingly; for in five hundred years at the outside our stock will be gone, and we shall sink to a third-rate Power at once.  We are sacrificing the future in order to provide for an excessive and discontented population in the present.  During the present century we have begun to be conscious that our foreign trade is threatened; and so sensitive is the birth-rate to economic conditions that it has begun to curve very slightly downward in relation to the death-rate, instead of descending with it in parallel lines.[23] This may be partly due to the curtailment of facilities for emigration, owing to the filling up of the new countries.  For emigration does not diminish the population of the country which the emigrants leave; it only increases its birth-rate.