When the progress of industry has augmented numbers, and made subsistence scarce, he must estimate to what height it is expedient that the price of subsistence should rise. If he finds, that, in order to encourage the breaking up of new lands, the price of it must rise too high, and stand high too long, to preserve the intrinsic value of goods at the same standard as formerly; then he must assist agriculture with his purse, in order that exportation may not be discouraged. This will have the effect of increasing subsistence, according to the true proportion of the augmentation required, without raising the price of it too high. And if that operation be the work of time, and the demand for the augmentation be pressing, he must have subsistence imported, or brought from abroad, during that interval. This supply he may cut off whenever he pleases, that is, whenever it ceases to be necessary. If the supply comes from a sister country, it must be so taken, as to occasion no violent revolution when it comes to be interrupted a-new. As for example: One province demands a supply of grain from another, only for a few years, until their own soil can be improved, so as to provide them sufficiently. The statesman should encourage agriculture, no doubt, in the province furnishing, and let the farmers know the extent of the demand, and the time it may probably last, as near as possible; but he must discourage the plucking up of vineyards, and even perhaps the breaking up of great quantities of old pasture; because, upon the ceasing of the demand, such changes upon the agriculture of the province furnishing, may occasion a hurtful revolution. While this foreign supply is allowed to come in, the statesman should be closely employed in giving such encouragement to agriculture at home, according to the principles hereafter to be deduced, as may nearly balance the discouragement given to it by this newly permitted importation. If this step be neglected, the consequence may be, that the foreign supply will go on increasing every year, and will extinguish the agriculture already established in the country, in place of supplying a temporary exigency, which is within the power of the country itself to furnish. These, I suppose, were the principles attended to by the government of England, upon opening their ports for the importation of provisions from Ireland. The principle, therefore, being to support a gentle increase of food, inhabitants, work, and demand, the statesman must suffer small vibrations in the balance, which, by alternate competition, may favour both sides of the contract; but whenever the competition stands too long upon either side, and threatens a subversion of the balance, then, with an artful hand, he must endeavour to load the lighter scale, and never, but in cases of the greatest necessity, have recourse to the expedient of taking any thing from the heaviest.