For if Nature can and does increase fertility to prevent the extinction of a species by excessive mortality, need we doubt that she can and will decrease it to prevent its extinction by overcrowding? It is certain that she does, in a mysterious way, respond to our necessities, or rather to her own. But her way is one that we do not understand. The people who say that if we improve the condition of the world it will be overpopulated are only pretending to understand it. If the Socialists were to say positively that Nature will keep the population within bounds under Socialism without artificial birth control, they would be equally pretending to understand it. The sensible course is to improve the condition of the world and see what will happen, or, as some would say, trust in God that evil will not come out of good. All that concerns us at present is that as the overpopulation difficulty has not yet arisen except in the artificial form produced by our unequal distribution of income, and curable by a better distribution, it would be ridiculous to refrain from making ourselves more comfortable on the ground that we may find ourselves getting uncomfortable again later on. We should never do anything at all if we listened to the people who tell us that the sun is cooling, or the end of the world coming next year, or the increase of population going to eat us off the face of the earth, or, generally, that all is vanity and vexation of spirit. It would be quite sensible to say “Let us eat and drink; for tomorrow we die” if only we were certain about tomorrow; but it would be foolish anyhow to say “It is not worth while to live today; for we shall die tomorrow”. It is just like saying “It will be all the same a thousand years hence” as lazy people do when they have neglected their duties. The fact is that the earth can accommodate its present population more comfortably than it does or ever did; and whilst we last we may as well make ourselves as comfortable as we can. Note that as long as two persons can produce more than twice as much as one, and two million very much more than twice as much as one million, the earth is said by the political economists to be under the Law of Increasing Return. And if ever we reach a point when there will be more people than the earth can feed properly, and the next child born will make the whole world poorer, then the earth will be under the Law of Diminishing Return. If any gentleman tries to persuade you that the earth is now under the Law of Diminishing Return you may safely conclude that he has been told to say so at a university for the sons of the rich, who would like you to believe that their riches, and the poverty of the rest, are brought about by an eternal and unchangeable law of Nature instead of by an artificial and disastrous misdistribution of the national income which we can remedy.