The object of the one is the restoration, with increase, in some new form, of that which is consumed. The object of the other is the enjoyment of some good through the sacrifice of that which is consumed.
That which is consumed productively is capital, reappearing for future use. That which is consumed unproductively ceases to be capital, or any thing else. It is wholly lost.
Such loss is desirable or the contrary in proportion as the happiness resulting from the sacrifice exceeds or falls short of the happiness belonging to the continued possession of the consumable commodity.
The total of what is produced is called the gross produce.
That which remains, after replacing the capital consumed, is called the net produce.
While a man produces only that which he himself consumes, there is no demand and supply.
If a man produces more of one thing than he consumes, it is for the sake of obtaining something which another man produces, over and above what he consumes.
Each brings the two requisites of a demand; viz., the wish for a supply, and a commodity wherewith to obtain it.
This commodity, which is the instrument of demand, is, at the same time, the instrument of supply.
Though the respective commodities of no two producers may be exactly suitable to their respective wishes, or equivalent in amount, yet, as every man’s instrument of demand and supply is identical, the aggregate demand of society must be precisely equal to its supply.