Finding it impossible to limit Fisher to any single statement of the quantitative importance of his normal theory as compared with the other tendencies at work, but concluding that, on the whole, he considers it of high importance, I shall now proceed to an analysis of the reasoning by which he seeks to justify it as a _qualitative_ tendency. I shall maintain that, however long or short the period required, however strong or weak the tendency he defends, the reasoning by which he seeks to justify it is unsound, and that even as a qualitative tendency, the quantity theory is invalid. At a later part of the book, as in an earlier part,[194] I shall undertake to find the modicum of truth which the quantity theory contains, and shall show that no quantity theory is needed to exhibit this modicum of truth. CHAPTER XI BARTER In the statement of the quantity theory, the proviso is commonly made that all exchanges must be made by means of money, or of money and bank-credit. Barter is excluded by hypothesis. If resort to barter were possible, then people might avert the fall in prices due to scarcity of money, or increase in trade, by dispensing with money in part of their transactions, and the proportional decrease in prices which the quantity theory calls for would be lacking. Is this assumption true? Is barter banished from the modern world, or does it remain reasonably possible, and, to a considerable degree, actual? Fisher maintains the thesis--the failure of which he admits would spoil the quantity theory[195]--that barter is practically impossible, and negligible in modern business life. "Practically, however, in the world to-day, even such temporary resort to barter is trifling. The convenience of exchange by money is so much greater than the convenience of barter, that the price adjustment would be made almost at once. If barter needs to be seriously considered as a relief from money stringency, we shall be doing it full justice if we picture it as a safety valve, working against a resistance so great as almost never to come into operation, and then only for brief transition intervals. For all practical purposes and all normal cases, we may assume that money and checks are necessities for modern trade."[196] This contention seems to me untenable. I think it can easily be shown that barter remains an important factor in modern business life, especially if one extends the term barter, a little, to cover various flexible substitutes for the use of money and checks in effecting exchanges. Clearly from the standpoint of the present issue, such an extension of the meaning of barter is legitimate, as any such substitutes would equally spoil the proportionality in the supposed relation between prices and money, or prices and trade.