CONCEPTIONS AND METHODS OF ECONOMICS 11 



abstract ideal of usufruct, therefore, is that of an income yielded by 

 an everlasting agent. 



Such a typical example is rarely presented by any concrete good. 

 Though the conception of usufruct is always in some measure an 

 abstraction rather than a fact, yet usufruct is a practical abstraction 

 indispensable to the understanding of value problems. In practice 

 a particular concrete agent may partake in varying degrees of the 

 nature of a consumption good whose utility vanishes in affording 

 gratification, and of the nature of a usufruct bearer, whose power to 

 afford a series of gratifications is unimpaired by the successive uses. 

 So essential is this conception in practical business that various 

 devices are adopted, such as repair- and sinking-funds, to give the 

 similitude of durability to agents which are gradually wearing out. 

 The confusion of the conception of usufruct with other conceptions 

 has been especially unfortunate in the treatment of rent. 



Time-value. - - The conception of the value problem has widened 

 through the centuries. The elemental phase of value, recognized 

 even by animals, is found in a consumption good, of substance and 

 material to afford gratification here and now. Primitive man 

 recognizes in addition to this the factor of form, and sees in a fitting 

 change of shape a rational cause of value. Many thousands of years 

 elapsed before the change of place ceased to be a mysterious factor in 

 value, and still in the late Middle Ages the merchant,, the shipper, 

 and other agents of transportation, seemed to the mass of men to be 

 unproductive parasites upon the social organism. Even the over- 

 whelming evidence of the senses and the estimates of all men showing 

 that value was by these agencies imparted to goods did not, until of 

 late, shake the stubbornly materialistic conception that value 

 lay in the form and substance of things rather than in their psycho- 

 logical relations. 



The time-relation proved to be still more subtle and difficult for 

 the concrete minds of men to comprehend. The chapter of eco- 

 nomic history dealing with the cruder aspect of the time-value 

 problem, the notions of, and opposition to, interest on money loans, 

 is familiar. Let us venture the more novel opinion that even certain 

 subtle current conceptions of the interest problems are mixed with 

 the dross of cruder materialistic thought, in that the theorists 

 persist in finding the essence of the problem of interest in the par- 

 ticular class of concrete agents with which interest is supposed to be 

 connected. 



Economic theory is now ripe for the fundamental conception of 

 time-value as the difference in value of goods of any kind in dif- 

 ferent periods of time. Time-difference is a pervasive factor in the 

 valuation of the simplest goods and the simplest economic societies, 

 but so long as industry is concerned mainly with the present and a 



