It follows, from the preceding analysis, that rent depends on the prices realized by agricultural produce compared with the cost of their production, the farming profits included. A high price does not in every case imply a correspondingly high rent, for the cost of raising agricultural produce varies immensely in different localities; still, as a rule, elevated prices will raise up rents with them. The same truth holds good of every business: it must yield repayment of all cost of manufacturing, and reward the manufacturer with the necessary profit, or it will cease to exist. But agricultural price encounters two serious embarrassments not to be found to an equal degree in other trades. It is, in the first place, powerfully acted upon by the vicissitudes of the weather: a bountiful harvest, coming in contact with great commercial profits, brings a full and often an augmented price, to the great advantage of the farmer; a poor harvest, falling on a depressed trade, often fails to reap a price corresponding with the diminution of the supply. There is but one remedy wherewith to meet the fluctuations of such a market--a remedy, unfortunately, too little heeded by most farmers. The great law of the average harvest must be ever borne in mind, ought ever to govern the conduct of the intelligent farmer: he is bound, by the very nature of his business, to reserve the excess of profits of the good year to balance the deficient return of the failing crop. His rent ought to be, probably is, founded on this principle; his practice often exhibits profuse self-indulgence under the temptations of the prosperous time, in utter thoughtlessness about the future. We have now reached the full explanation of rent. It is surplus profit--that is, excess of profit after the repayment of the whole cost of production, beyond the legitimate profit which belongs to the tenant as a manufacturer of agricultural produce. The interest which he would have reaped from placing capital which he has devoted to the farm in some safe investment, such as consols or railway debentures, forms necessarily a portion of the cost of production. He would have realized some 4 per cent. on the investment without risk or effort of any kind. This interest constitutes no reward for engaging in agriculture.