Malthus bases farm-rent upon the principle of commerce.
Now, the fundamental law of commerce being equivalence of the products exchanged, any thing which destroys this equivalence violates the law.
There is an error in the estimate which needs to be corrected.
Buchanan--a commentator on Smith--regarded farm-rent as the result of a monopoly, and maintained that labor alone is productive.

Consequently, he thought that, without this monopoly, products would rise in price; and he found no basis for farm-rent save in the civil law.

This opinion is a corollary of that which makes the civil law the basis of property.
But why has the civil law--which ought to be the written expression of justice--authorized this monopoly?
Whoever says monopoly, necessarily excludes justice.

Now, to say that farm-rent is a monopoly sanctioned by the law, is to say that injustice is based on justice,--a contradiction in terms.
Say answers Buchanan, that the proprietor is not a monopolist, because a monopolist "is one who does not increase the utility of the merchandise which passes through his hands." How much does the proprietor increase the utility of his tenant's products?
Has he ploughed, sowed, reaped, mowed, winnowed, weeded?
These are the processes by which the tenant and his employees increase the utility of the material which they consume for the purpose of reproduction.
"The landed proprietor increases the utility of products by means of his implement, the land.

This implement receives in one state, and returns in another the materials of which wheat is composed.