Some of the labour stored and the capital established in the construction of harbours, the drainage of land, the construction of scientific instruments, and other works of durable nature and indirect service, may not be represented in consumptive goods for centuries. Admitting this, it may be urged, can any limits be set to present "saving" and its storage in forms of capital, provided those forms be selected with a due regard to a sufficiently distant future? The answer is that only under two conditions could an indefinitely large amount of present "saving" be justified. The first condition is that an unlimited proportion of this "saving" can be stored in forms which are practically imperishable; the second condition is that our present foresight shall enable us to forecast the methods of production and consumption which shall prevail in the distant future. In fact neither of these conditions exists. However much present "saving" we stored in the most enduring forms of capital with which we are acquainted--_e.g._, in the permanent way of railroads, in docks, in drainage and improvement of land, a large proportion of this "saving" would be wasted if the consumption it was destined to subserve was postponed for long.[167] Neither can we predict with any assurance that the whole value of such "savings" will not have disappeared before a generation has elapsed by reason of changes in industrial methods. The amount of present "saving" which is justified from the point of view of the community is strictly limited. We cannot forecast the demand of our twentieth generation of descendants, or the industrial methods which will then prevail; we do not even know whether there will be a twentieth generation; there are certain large inevitable wastes in postponed consumption by reason of the perishability of all material forms of wealth, or the abstraction of them by others than those for whose use they were intended. Moreover, we do not believe it would be good for our descendants to have the enjoyment of excessive wealth without a corresponding personal effort of producing, nor would it be good for us to exert effort without some proximate and corresponding enjoyment. The limits of individual life rightly demand that a large proportion of individual effort shall fructify in the individual life.