are things of which it is physically impossible to increase the quantity beyond certain narrow limits. Such are those wines which can be grown only in peculiar circumstances of soil, climate, and exposure. Such also are ancient sculptures; pictures by old masters; rare books or coins, or other articles of antiquarian curiosity. Among such may also be reckoned houses and building-ground, in a town of definite extent (such as Venice, or any fortified town where fortifications are necessary to security); the most desirable sites in any town whatever; houses and parks peculiarly favoured by natural beauty, in places where that advantage is uncommon. Potentially, all land whatever is a commodity of this class; and might be practically so, in countries fully occupied and cultivated.
But there is another category (embracing the majority of all things that are bought and sold), in which the obstacle to attainment consists only in the labour and expense requisite to produce the commodity. Without a certain labour and expense it cannot be had: but when any one is willing to incur these, there needs be no limit to the multiplication of the product. If there were labourers enough and machinery enough, cottons, woollens, or linens might be produced by thousands of yards for every single yard now manufactured. There would be a point, no doubt, where further increase would be stopped by the incapacity of the earth to afford more of the material. But there is no need, for any purpose of political economy, to contemplate a time when this ideal limit could become a practical one.
There is a third case, intermediate between the two preceding, and rather more complex, which I shall at present merely indicate, but the importance of which in political economy is extremely great. There are commodities which can be multiplied to an indefinite extent by labour and expenditure, but not by a fixed amount of labour and expenditure. Only a limited quantity can be produced at a given cost: if more is wanted, it must be produced at a greater
