In various ways, as this volume shows, the war has profoundly affected our economic and political life. War has ever been a disturber and innovator, always leaving after it a different world from that which existed previous to it. On account of our tremendously complex economic organization--the specialization of industry among nations, and the network of commerce--war today causes more profound changes than ever before. There can not be a human being in the world today whose life is not altered by the war through which we have just passed. In trying, now that the war is over, to _stop drifting_, and to think our way out of the bent (or broken) remains of the _ante bellum_ life, the world is confronted by a maze of problems and a still greater maze of proffered solutions. Many of these proposals are, unfortunately, of the nature of treatment directed not at fundamental conditions, but merely at _symptoms_. We should be past the stage, in our social science, as we are in medicine, where we treat symptoms without a thorough diagnosis of the fundamental causes. And yet it is just this thorough diagnosis that we lack. What, then, are the changes brought about by the war which most deeply affect "the body politic," and by meeting which the most far reaching improvements can be made? HIGH COST OF LIVING A VITAL QUESTION I can not take up, or even touch on, all of them; but to one of them I wish to call especial attention--the High Cost of Living or, more generally, the high level of prices, which is the most striking economic effect of the war throughout the world. It is, as I see it, hard to over-emphasize the need for attacking this problem of the price level as a preliminary to attacking the other economic problems which the war has left us. We need only glance at a newspaper today, or step into a corner grocery, or fall into conversation with our neighbor in the train to have this topic come out as foremost in interest. It is, I believe, responsible for much more of our present uncertainty and confusion than is usually realized. In its ramifications it is chiefly this phase of the war's effects which, as I suggested above, touches every one of us at every point of our lives. A member of the Federal Reserve Board has called the price level problem _the_ central economic problem of reconstruction. Professor William Graham Sumner, who has inspired so many to the scientific study of social conditions, used to say: "In taking up the study of any social situation, divide your study into four questions--(1) What is it? (2) Why is it? (3) What of it? (4) What are you going to do about it?" Let us follow this outline, and look first at the facts of the case; secondly at their causes; thirdly at the evils involved; and lastly at the remedies. MEASURING CHANGES IN PRICES We now possess a device for measuring the average change in prices. This is what is known as an "index number."