Labour is the source of all wealth, the political economists assert. And it really is the source — next to nature, which supplies it with the material that it converts into wealth. But it is even infinitely more than this. It is the prime basic condition for all human existence, and this to such an extent that, in a sense, we have to say that labour created man himself.

The Part Played by Labour in the Transition from Ape to Man (1876)