If a commodity were in no way useful, - in other words, if it could in no way contribute to our gratification, - it would be destitute of exchangeable value, however scarce it might be, or whatever quantity of labour might be necessary to procure it.

If the quantity of labour realized in commodities, regulate their exchangeable value, every increase of the quantity of labour must augment the value of that commodity on which it is exercised, as every diminution must lower it.

If the demand for home commodities should be diminished, because of the fall of rent on the part of the landlords, it will be increased in a far greater degree by the increased opulence of the commercial classes.

David Ricardo Quotes