3. _In early stages of industry the use of nearly all wealth is estimated under the renting contract._ In the lower stages of culture, in hunting, fishing, or nomadic pastoral tribes, land is not recognized as wealth to be exchanged or owned. But at a later stage, as in the Middle Ages in Europe, land and the things pertaining to it, as ditches, houses, mills, cattle, stock, and the few simple implements, constituted the larger portion of the wealth. Land was granted to the tenant or serf in return for services. The contract was pretty strictly drawn and all items were specified. It was not hard to hold the tenant to his contract to keep the land in about the same condition. There was a certain rotation of crops; the tenant was obliged to keep his stock up to standard; and, moreover, he had a certain interest in the land because his contract rent (as explained above) was less than the economic rent. The landlord, therefore, could count pretty surely on the undiminished power of his land and stock from one year to another. At that time, truck and barter were the common modes of exchange, and rents were paid in products and services, not in money. The fruits of the soil were consumed on the spot instead of being sold as now. Land was rarely, if ever, sold outright, so that there was no occasion to estimate its total selling value. It was thought of as a place on which to live and as a source of livelihood. Its yearly use was all that was subject to contract, sale, and exchange. Not the land itself but a _rent charge_ on the land was sold, the term rent charge meaning an annual sum payable out of the yield of an estate. Many medieval estates were so tied up by legal conditions that they could not be sold outright; all that the owner could do was to sell or mortgage the annual rental. Thus, in the Middle Ages, it was all but universal to look upon most indirect agents as exchangeable only under the renting contract, as subject to renting but not to complete transfer and sale. [Sidenote: The renting contract not convenient in commerce]