Some control, therefore, may be exercised over the value of money under a convertible system, to make such value constant, but this is evidently limited. If the value of the money is falling, the decline can be checked, and its value made to rise, by withdrawing some of the paper issues; but this will cause an importation of coin, partly offsetting the reduction and checking such rise, and when all the paper has been withdrawn, the power of control by this method ceases. If the money value is rising, an increase of paper issues will stop such rise, but it will cause the exportation of coin; and when all the coin has been exported, the money will cease to be convertible, and the system will have changed to an inconvertible one,--the money still possessing the same qualifications as a measure of value that it possessed in the former case. The only difference is, that in the convertible system the money value is partly determined by the natural causes affecting the supply of coin, partly by the laws and conditions of business in foreign countries, and partly by the legislation at home, restricting the coinage or the issue of paper; while in the inconvertible system it is determined wholly by the control of the issues relative to the demand for money. This difference may constitute either a merit or a defect, according as the control is intelligent and honest or otherwise. The disastrous consequences that have resulted at various times from the use of inconvertible paper money, have, in every case, been due to a lack of proper control and to excessive issues, caused generally by the want of a reliable gauge by which to determine the amount that should be issued, and by a misunderstanding of the principles involved. While paper money, though a promise to pay coin, cannot, in one sense, be called honest, unless the promise is kept; in a larger sense the test of its honesty is its invariability of value. John Stuart Mill says of inconvertible paper money:-- "In the case supposed, the functions of money are performed by a thing which derives its power of performing them solely from convention; but convention is quite sufficient to confer the power; since nothing more is needful to make a person accept anything as money, and even at any arbitrary value, than the persuasion that it will be taken from them on the same terms by others. The only question is, what determines the value of such a currency; since it cannot be, as in the case of gold and silver (or paper exchangeable for them at pleasure), the cost of production. We have seen, however, that even in the case of metallic currency, the immediate agency in determining its value is its quantity. If the quantity, instead of depending on the ordinary mercantile motives of profit and loss, could be arbitrarily fixed by authority, the value would depend on the fiat of that authority, not on the cost of production.