2. _The gradual rise of a consumption good with the lapse of time from the lower to the higher degree of gratification is the rent it yields._ The difference in value of present and future rents is expressed by the discount of the future use when it is capitalized at any earlier moment, and emerges in the rise in value as the thing approaches to the time when it can render the later use. Next year the unit whose use is deferred will afford as much gratification as the earlier units do now, and more than if used at the present moment. The importance of any present utility is compared with its importance a year later, plus interest at a rate which expresses the limit to which future uses are discounted. Anything that makes men feel more the importance of future uses causes them to value those uses more. But the pressure of present want is such that a present use of a lower order competes with a future use of a higher order. Only goods of a lower order, nearer the margin, are reserved for the future. But just as the possibility of using a thing for several different purposes at present causes it to be valued more highly than if it had but one use, so the possibility of reserving to the future a portion of a stock imparts to every unit a higher marginal utility. [Sidenote: Interest is the equalizer of time values] 3. _The saving of present goods for future use is encouraged by the motive of gaining the interest._ Many consumption goods grow into higher uses in the hands of the owner, whether he uses them for himself or not. Ice may be stored in midwinter when it is all but a free good and a little labor serves to fill the ice-house. Kept until the summer months, the ice rises in value as the desire for it grows. Likewise the higher price secured by the owner of a thing kept for sale to others, reflects the change in utility, and affords practically a rent which is the motive for investing capital in that business. Any saver or abstainer puts aside present wants only when the future good, with the addition of time-value or of money interest, appears as large as the present good. Interest is therefore the equalizer of the value of things in different periods. Put into the scale of judgment when present and future are compared, it helps to balance the disparity in the gratifications given by economic goods in different periods of time. [Sidenote: Saving increases and improves economic agents]