===Part 3: Of the Variations in the Proportion between the respective Values of that Sort of Produce which always affords Rent, and of that which sometimes does and sometimes does not afford Rent===

The increasing abundance of food, in consequence of increasing improvement and cultivation, must necessarily increase the demand for every part of the produce of land which is not food, and which can be applied either to use or to ornament. In the whole progress of improvement, it might therefore be expected, there should be only one variation in the comparative values of those two different sorts of produce. The value of that sort which sometimes does and sometimes does not afford rent, should constantly rise in proportion to that which always affords some rent.

As art and industry advance,