Let me first briefly state the second point of my criticism of these studies: namely, that even if the statistics are correct, they do not constitute proof of the quantity theory. The statistics purport to be concrete data filling out for different years the equation of exchange.[378] But the equation of exchange, as we have seen, does not prove the quantity theory. The quantity theory is a _causal_ theory, and causation involves an order _in time_. The concrete figures for the equation do not prove that. Even Kemmerer's concluding chart on p. 148, showing a rough concomitance between "relative circulation" and general prices does not show that changes in relative circulation are _causes_ of changes in general prices. The causation might be the reverse for anything his figures tell us. Fisher himself recognizes this, in considerable degree: "As previously remarked, to establish the equation of exchange is not completely to establish the quantity theory of money, for the equation does not reveal which factors are causes and which are effects."[379] Again: "But, to a candid mind, the quantity theory, in the sense in which we have taken it, ought to appear sufficiently secure without such checking. Its best proof must be _a priori_."[380] The main criticism here, however, relates to the figures themselves, rather than to their meaning. The figures given by Professor Fisher are concrete magnitudes to fill out his equation of exchange, MV + M'V' = PT[381] for the years since 1896. Thus, for 1909, the figures are: M = 1.61 billions; M' = 6.68 billions; V = 21.1; V' = 52.8; P = $1; T = 387 billions.[382] Now in what follows, I shall challenge all these estimates except P for 1909, V for 1896 and 1909, and M and M' for all years. The figures for M and M', being the results of fairly simple computations based on Governmental statistics, need not be questioned. P for 1909 is arbitrarily placed at $1.00. V for 1896 and 1909, for reasons which will later appear, is better based than for other years, though Kemmerer and Fisher have differed greatly in their estimates for V, the former placing it at 47 and the latter at 18 or 20.[383] My criticisms with reference to V, however, will relate to the years other than 1909 and 1896.