The lowest rate of profit that can permanently exist is that which is barely adequate, at the given place and time, to afford an equivalent for the abstinence, risk, and exertion implied in the employment of capital. From the gross profit has first to be deducted as much as will form a fund sufficient on the average to cover all losses incident to the employment. Next, it must afford such an equivalent to the owner of the capital for forbearing to consume it as is then and there a sufficient motive to him to persist in his abstinence. How much will be required to form this equivalent depends on the comparative value placed, in the given society, upon the present and the future (in the words formerly used): on the strength of the effective desire of accumulation. Further, after covering all losses, and remunerating the owner for forbearing to consume, there must be something left to recompense the labor and skill of the person who devotes his time to the business. Such, then, is the minimum of profits: but that minimum is exceedingly variable, and at some times and places extremely low, on account of the great variableness of two out of its three elements. That the rate of necessary remuneration for abstinence, or in other words the effective desire of accumulation, differs widely in different states of society and civilization, has been seen in a former chapter. There is a still wider difference in the element which consists in compensation for risk. The remuneration of capital in different employments, much more than the remuneration of labor, varies according to the circumstances which render one employment more attractive or more repulsive than another. The profits, for example, of retail trade, in proportion to the capital employed, exceed those of wholesale dealers or manufacturers, for this reason among others, that there is less consideration attached to the employment. The greatest, however, of these differences, is that caused by difference of risk. The profits of a gunpowder-manufacturer must be considerably greater than the average, to make up for the peculiar risks to which he and his property are constantly exposed. When, however, as in the case of marine adventure, the peculiar risks are capable of being, and commonly are, commuted for a fixed payment, the premium of insurance takes its regular place among the charges of production, and the compensation which the owner of the ship or cargo receives for that payment does not appear in the estimate of his profits, but is included in the replacement of his capital.