invested per acre’’. Marx calls this Differential rent II and he examines what would be the effect of more capital-intensive agriculture when the production price remains stable, and when it falls, while the extra yield from additional capital investments varies. Summary The theory of Differential rent I shows how extra profit is transformed into rent by equal quantities of capital being invested on different lands of unequal productivity, while the theory of Differential Rent II refers to the difference in profitability resulting from unequal amounts of capital being invested successively and intensively on different plots of land of the same type. Differential rent II implies the appropriation of surplus profits created by temporary differences in yield, which are due to the application of unequal capitals to the same type of lands. Absolute ground rent The absolute ground rent is sometimes explained as the rent which landowners can extract because they monopolise the access to or supply of land, and sometimes as the rent which arises due to the difference between the product-values and prices of production of output in agriculture, because of a lower than average organic composition of capital in agriculture as compared with industry. According to Marx's own concept, absolute rent cannot exist when the organic composition of capital in agriculture becomes higher than the social average. Marx envisaged that labour productivity would be higher in manufacturing than in agriculture, for the longer term, reflecting the fact that the organic composition of capital (the ratio C/V) was higher in manufacturing than in agriculture. This implied, that in agriculture the value of output produced was persistently higher than the production price of that output. Physiocratic school Another definition for ground rent or absolute ground rent originates from the 18th-century French school of political economy called the Physiocrats. They sought to bring logical analysis to bear on governmental questions. They arrived at the conclusion that "ground rents" should be the source of most or all taxes. They defined ground rent as that portion of all rent which is attributable only to the size and location of the parcel. For instance, say you own a parcel of land. If everything you grew or built on that land burned . . . then you could still lease it out for its ground rent (its locational value). The Physiocrats noted that the owner is in no way responsible for any increase in the