3. A third very important deduction follows from the nature of the process which determines rent. Rent does not increase the price of agricultural produce; it does not make bread dearer. Rent is the consequence, not the creator, of price. Here the difference between agriculture and manufacturing trades is vital. The hire or purchase of machinery forms necessarily a part of the cost of manufacturing the goods: it must be paid for by the price realized, or the goods will not be made. On the other hand, the consideration to be given for the use of the land does not enter into the tenant's estimate of his cost of production. He does not direct his inquiry to the right rent till after he has ascertained what the farm will produce, the cost of obtaining it, and the price it will fetch. He then discovers what the profit will be: from it he takes his own necessary share; what is over he hands to the landlord as rent. He does not, like the manufacturer, insist upon a price which must be obtained, for otherwise he would not be able to pay for the use of the machine he borrows; he simply takes the price which he finds in the market, makes himself reasonably sure of the profit which rewards him, and the landlord must take the chance of what rent will remain over, whether large or small. Rent exists because a selling price is found which yields a surplus, an excess of profit beyond what the tenant requires. If price gives no surplus profit, the landlord will get no rent, and he must farm the land himself, or sell it to a farmer.