[which give greater or less wages of superintendence], [pg 221] the rate of profit on capital in all employments tends to an equality. That portion of profit which is properly interest, and which forms the real remuneration for abstinence, is strictly the same at the same time and place, whatever be the employment. The rate of interest, on equally good security, does not vary according to the destination of the principal, though it does vary from time to time very much, according to the circumstances of the market.
It is far otherwise with gross profit, which, though (as will presently be seen) it does not vary much from employment to employment, varies very greatly from individual to individual, and can scarcely be in any two cases the same. It depends on the knowledge, talents, economy, and energy of the capitalist himself, or of the agents whom he employs; on the accidents of personal connection; and even on chance. Hardly any two dealers in