If tools, buildings, and materials were the spontaneous gifts of nature,
requiring no labour either in order to produce or to appropriate them;
and if they were thus bestowed upon mankind in indefinite quantity, and
without the possibility of being monopolized; they would still be as
useful, as indispensable as they now are; but since they could, like air
and the light of the sun, be obtained without cost or sacrifice, they
would form no part of the expenses of production, and no portion of the
produce would be required to be set aside in order to replace the outlay
made for these purposes. The whole produce, therefore, after replacing
the wages of labour, would be clear profit to the capitalist.

Labour alone is the primary means of production; "the original
purchase-money which has been paid for everything." Tools and materials,
like other things, have originally cost nothing but labour; and have a
value in the market only because wages have been paid for them. The
labour employed in making the tools and materials being added to the
labour afterwards employed in working up the materials by aid of the
tools, the sum total gives the whole of the labour employed in the
production of the completed commodity. In the ultimate analysis,
therefore, labour appears to be the only essential of production. To
replace capital, is to replace nothing but the wages of the labour
employed. Consequently, the whole of the surplus, after replacing wages,
is profits. From this it seems to follow, that the ratio between the
wages of labour and the produce of that labour gives the rate of profit.
And thus we arrive at Mr. Ricardo's principle, that profits depend upon
wages; rising as wages fall, and falling as wages rise.

To protect this proposition (the most perfect form in which the law of
profits seems to have been yet exhibited) against misapprehension, one
or two explanatory remarks are required.