In On the Principles of Political Economy and Taxation (1817) Ricardo defined rent as the payment for the use of the original and indestructible powers of the soil, arising because land differs in fertility and in situation. Cultivation extends to the worst land that will just cover its costs; that margin sets the price, and every better site earns the difference as rent. Rent is therefore a residual rather than a cost of production - corn is not dear because rent is paid, rent is paid because corn is dear. The corollary, which he drew himself, is that landowners capture the gains of growth without contributing to it.
This is the foundation of all land economics: site value as a residual set by what a location yields or saves relative to the margin. It runs straight into von Thünen's gradient, Henry George's single tax, Alonso's bid-rent surface, and every present-day argument about betterment, land value capture and who should own the uplift created by a new railway.
See it on the timeline →