The abstract idea, then, of just or due wages, as respects the labourer, is that they will consist in a sum of money which will at any time procure for him at least as much labour as he has given, rather more than less. And this equity or justice of payment is, observe, wholly independent of any reference to the number of men who are willing to do the work. I want a horseshoe for my horse. Twenty smiths, or twenty thousand smiths, may be ready to forge it; their number does not in one atom's weight affect the question of the equitable payment of the one who _does_ forge it. It costs him a quarter of an hour of his life, and so much skill and strength of arm to make that horseshoe for me. Then at some future time I am bound in equity to give a quarter of an hour, and some minutes more, of my life (or of some other person's at my disposal), and also as much strength of arm and skill, and a little more, in making or doing what the smith may have need of. Such being the abstract theory of just remunerative payment, its application is practically modified by the fact that the order for labour, given in payment, is general, while the labour received is special. The current coin or document is practically an order on the nation for so much work of any kind; and this universal applicability to immediate need renders it so much more valuable than special labour can be, that an order for a less quantity of this general toil will always be accepted as a just equivalent for a greater quantity of special toil. Any given craftsman will always be willing to give an hour of his own work in order to receive command over half an hour, or even much less, of national work. This source of uncertainty, together with the difficulty of determining the monetary value of skill,[40] renders the ascertainment (even approximate) of the proper wages of any given labour in terms of currency, matter of considerable complexity. But they do not affect the principle of exchange. The worth of the work may not be easily known; but it _has_ a worth, just as fixed and real as the specific gravity of a substance, though such specific gravity may not be easily ascertainable when the substance is united with many others. Nor is there so much difficulty or chance in determining it as in determining the ordinary maxima and minima of vulgar political economy. There are few bargains in which the buyer can ascertain with anything like precision that the seller would have taken no less;--or the seller acquire more than a comfortable faith that the purchaser would have given no more. This impossibility of precise knowledge prevents neither from striving to attain the desired point of greatest vexation and injury to the other, nor from accepting it for a scientific principle that he is to buy for the least and sell for the most possible, though what the real least or most may be he cannot tell. In like manner, a just person lays it down for a