Now the trouble with the main proposition just quoted is that each side of the equation is used as the measure of the other. In order to show what natural price is, we add up all the wages that have been paid, and declare that to be the cost and then say that the cost governs the price. Then if we are asked why are wages what they are, we turn the argument backward and say that since the selling price is so and so the wages that can be paid out of it only amount to such and such. This explains nothing. It is a mere argument in a circle. It is as if one tried to explain why one blade of a pair of scissors is four inches long by saying that it has to be the same length as the other. This is quite true of either blade if one takes the length of the other for granted, but as applied to the explanation of the length of the scissors it is worse than meaningless. This reasoning may seem to many persons mere casuistry, mere sophistical juggling with words. After all, they say, there is such a thing as relative cost, relative difficulty of making things, a difference which rests upon a physical basis. To make one thing requires a lot of labor and trouble and much skill: to make another thing requires very little labor and no skill out of the common. Here then is your basis of value, obvious and beyond argument. A primitive savage makes a bow and arrow in a day: it takes him a fortnight to make a bark canoe. On that fact rests the exchange value between the two. The relative quantity of labor embodied in each object is the basis of its value. This line of reasoning has a very convincing sound. It appears in nearly every book on economic theory from Adam Smith and Ricardo till to-day. "Labor alone," wrote Smith, "never varying in its own value is above the ultimate and real standard by which the value of all commodities can at all times and places be estimated and compared."