estimated in the very great addition which it makes to the capital and revenue of the country, in the most natural and ordinary acceptation of these terms. And when the effects of their genius have been estimated in this way, it would not only lead to inextricable difficulty, but it would be obviously a double entry, to estimate, in addition, the value of the men as extraordinary machines. It would be like estimating the value of a commodity produced by a skilful artificer, and then adding his high wages, and putting both into an estimate of national wealth. But it is difficult to say what may not be called wealth, or what labour may not be called productive, in Mr. Macculloch’s nomenclature. According to his view of the subject, any sort of exertion, or any sort of consumption which tends, however _indirectly_, to encourage production, ought to be denominated productive; and before we venture to call the most trivial sort of exercise or amusement, such as blowing bubbles, or building houses of cards unproductive, we must wait to see whether the person so employed does not work the harder for it afterwards.[38] But, not to mention the impossibility of any, the most useful classification, if such doctrines were admitted, and we were required to wait the result in each particular case, and make exceptions accordingly, I will venture to affirm, that if we once break down the distinction between the labour which is so directly productive of wealth as to be estimated in the value of the object produced, and the labour or exertion, which is so indirectly a cause of wealth, that its effect is incapable of definite estimation, we must necessarily introduce the greatest confusion into the science of political economy, and render the causes of the wealth of nations inexplicable. There is no kind of exertion or amusement which may not, upon this principle, be called productive. Walking, riding, driving, card-playing, billiard-playing, &c. &c. may all be, indirectly, causes of production; and according to Mr. Macculloch, “it is very like a truism, to say, that what is a cause of production must be productive.”[39] But of all the indirect causes of production, the most powerful, beyond all question, is consumption. If man were not to consume, how scanty, comparatively, would be the produce of the earth. Consumption, therefore, is the main fundamental cause of production; and if we are to put indirect causation on a footing with direct causation, as suggested by Mr. Macculloch, we must rank in the same class, the manufacturer and the billiard player, the producer and the consumer.