But the idea that _quantity of labor governs_ value will not stand examination for a moment. What is _quantity_ of labor and how is it measured? As long as we draw our illustrations from primitive life where one man's work is much the same as another's and where all operations are simple, we seem easily able to measure and compare. One day is the same as another and one man about as capable as his fellow. But in the complexity of modern industrial life such a calculation no longer applies: the differences of skill, of native ingenuity, and technical preparation become enormous. The hour's work of a common laborer is not the same thing as the hour's work of a watchmaker mending a watch, or of an engineer directing the building of a bridge, or of an architect drawing a plan. There is no way of reducing these hours to a common basis. We may think, if we like, that the quantity of labor _ought_ to be the basis of value and exchange. Such is always the dream of the socialist. But on a closer view it is shattered like any other dream. For we have, alas, no means of finding out what the quantity of labor is and how it can be measured. We cannot measure it in terms of time. We have no calculus for comparing relative amounts of skill and energy. We can not measure it by the amount of its contribution to the product, for that is the very matter that we want to discover. What the economist does is to slip out of the difficulty altogether by begging the whole question. He deliberately measures the quantity of labor _by what is paid for it_. Skilled labor is worth, let us say, three times as much as common labor; and brain work, speaking broadly, is worth several times as much again. Hence by adding up all the wages and salaries paid we get something that seems to indicate the total quantity of labor, measured not simply in time, but with an allowance for skill and technical competency. By describing this allowance as a coefficient we can give our statement a false air of mathematical certainty and so muddle up the essential question that the truth is lost from sight like a pea under a thimble. Now you see it and now you don't. The thing is, in fact, a mere piece of intellectual conjuring. The conjurer has slipped the phrase, "quantity of labor," up his sleeve, and when it reappears it has turned into "the expense of hiring labor." This is a quite different thing. But as both conceptions are related somehow to the idea of cost, the substitution is never discovered.