PART II FURTHER ELUCIDATIONS § I. The Supply of Currency and the *' Quantity Theory.” The sad experience of unlimited currencies which followed the writing of the First Part of this book do not suggest the desirability of abandoning or even modifying any part of the doctrine taught therein, but they do suggest that further elucidation of several matters is required. Some readers have asked, and others probably will ask, ‘“ What is the relation of this doctrine to the Quantity Theory of the value of money ? ” It includes the Quantity Theory, but contains something more. The Quantity Theory, like so many other statements in economic literature, insists that X ‘“ depends on A, other things being equal or remaining the same,” regardless of the fact that it would be equally true to say ‘“ X depends on B, other things (including A) being equal or remaining the same.” It is possible that there may be ten or a thousand things on which X depends, and of each of them it is true to say that it depends’on that one when the others are, as it is said, “‘ impounded in ceferis paribus.” Writers on economic questions frequently overlook this, and imagine themselves at variance about fundamentals, when in fact the only difference between them is that one is more struck by the importance of A and therefore says ‘“ X depends upon A, other things (including I} being equal,” while the 6c