Page:The wealth of nations, volume 1.djvu/89

 they could purchase or command less labor; and this revolution in their value, though perhaps the greatest, is by no means the only one of which history gives some account. But as a measure of quantity, such as the natural foot, fathom, or handful, which is continually varying in its own quantity, can never be an accurate measure of the quantity of other things; so a commodity which is itself continually varying in its own value can never be an accurate measure of the value of other commodities. Equal quantities of labor, at all times and places, may be said to be of equal value to the laborer. In his ordinary state of health, strength and spirits; in the ordinary degree of his skill and dexterity, he must always lay down the same portion of his ease, his liberty, and his happiness. The price which he pays must always be the same, whatever may be the quantity of goods which he receives in return for it. Of these, indeed, it may sometimes purchase a greater and sometimes a smaller quantity; but it is their value which varies, not that of the labor which purchases them. At all times and places that is dear which it is difficult to come at, or which it costs much labor to acquire; and that cheap which is to be had easily, or with very little labor. Labor alone, therefore, never varying in its own value, is alone the ultimate and real standard by which the value of all commodities can at all times and places be estimated and compared. It is their real price; money is their nominal price only.

But though equal quantities of labor are always of equal value to the laborer, yet to the person who employs him they appear sometimes to be of greater and sometimes of smaller value. He purchases them sometimes with a greater and sometimes with a smaller quantity of goods, and to him