Absolute rent (n.) is surplus-value that landed property stops from being shared out: an alien power blocks capital's equalizing flow, and the landowner keeps the dam.
Differential rent (n.) on the better soil rises when many farmers work with insufficient capital, and poorer farming on worse soil increases the rent on the better.
Differential rent (n.) does not require, as Ricardo and Malthus thought, a march to ever worse soil; its only precondition is that soils are unequal.
Differential rent (n.) lets the worst soil, bearing no rent, set the market price for all corn, unless the better soils produce more than is demanded, and in that way American grain prices govern English ones.
Differential rent (n.) arises, as with the waterfall-powered mill, not from selling above the price of production but from selling at it while producing below it.
Ground rent (n.) seems tied to a natural element rather than a social relation, and that completes the burial: the inner connection of surplus-value is torn asunder and its source completely buried.
Ground rent (n.) under capitalism falls from being the normal form of surplus labour to a mere leftover — the excess the capitalist hands over after taking his profit.
Ground rent (n.) called "natural" comes down to subtracting a sum of money from a bushel of wheat — worse than squaring the circle.
Ground rent (n.) reckoned as money per acre is an irrational ratio — like measuring a £5 note against the diameter of the earth; what it really means is that owning these square feet lets you seize unpaid labour that capital has rooted out of the soil like a pig in potatoes.
Rent in kind (n.) replaces the whip with circumstances: the peasant now drives himself to produce the lord's surplus, by legal stipulation rather than direct supervision.
Rent in kind (n.) gives the impression that rent comes from the earth and not from social relations — a ruin surviving from a dead mode of production.