But while the Lassallians, and before them the Ricardians, used the _phrase_, it is evident that they assumed the inclusion of what Marx calls "Nature." They know very well that labor, mere exertion of physical strength, could produce nothing. If, for instance, a man were to spend all his strength trying to lift the pyramids, alone and unaided by mechanical power, it is quite evident to the meanest intellect that his exertions would not produce a single atom of wealth. It is equally obvious that if we take any use-value, whether it be an exchange-value or not being immaterial, we cannot eliminate from it the substance of which it is composed. Take, for example, the canoe of a savage, which is a simple use-value, and a meerschaum pipe, which is a commodity. In the canoe we have part of the trunk of a tree taken from the primeval forest, one of Nature's products. But without the labor of the savage it would never have become a canoe. It would have remained simply part of the trunk of a tree, and would not have acquired the use-value it has as a canoe. But it is likewise true that without the tree the canoe could not have existed. So with our meerschaum pipe. It is not simply a use-value: it is also an article of commerce, an exchange-value, a commodity. Its elements are, the silicate mineral which Nature provided and the form which human labor has given it. We can apply this test to every form of wealth, whether simple use-values or commodities, and we shall find that, in Mill's phrase, wealth is produced by the application of human labor to _appropriate natural objects_.