150 ECONOMIC ESSAYS IN HONOR OF JOHN BATES CLARK 
general purchasing power.” * He declares that the idea of interest 
is strictly applicable only to fluid capital, evidently meaning 
readily available purchasing power. “The rate of interest is a 
ratio and the two things which it connects are both sums of 
money.” > Thus it appears that after many contradictory 
assertions and formal definitions that reaffirm the older Ricardian 
scheme, Marshall really uses capital in nearly all his discussions 
of price and of business problems in his later editions as an 
individual (acquisitive) concept, expressed in (market) valuation 
terms. Yet unsuspecting students still are led to seek in Marshall 
a source of theoretical illumination instead of a smoke cloud. 
Eri Re. 
a 
7. The Yale Economists 
The influence of Clark’s views of capital showed itself at Yale 
within the following decade in the writings of A. T. Hadley and 
of his younger colleague, Irving Fisher. Hadley published in 
1895 * a noteworthy article marked by an insight and a clarity in 
nearly every feature in advance of its date, and by a realism in 
advance of Clark’s abstraction of an entity of pure capital. 
Hadley recognized both the broad social and the narrow indivi- 
dual conception of wealth, and the broad and the narrow concep- 
tion of capital. “Individual wealth is more accurately designated 
as property.” “The capital of an individual is more accurately 
designated as an investment.” “A title to property is not neces- 
sarily productive as held by Clark.” Here Hadley briefly, but in 
essence, anticipated what Veblen (and in part Davenport) 
developed many years later regarding the contrast between 
acquisition and production, while avoiding Veblen’s exaggeration 
of the contrast and his caricature of the profit motive. Hadley’s 
text Economics published the next year, reproduced in its first 
chapter "(on Public and Private Wealth) the substance of this 
article, but with certain additions (unfortunate, in our view) 
involving, as Hadley says,* “a combination of the ideas of Knies 
and Newcomb,” but for which he acknowledges his chief indebted- 
ness to be due to his colleague, Dr. Irving Fisher. 
The essential addition due to Fisher was a distinction between 
yi 
1E.g. idem. p. 411. 
® Idem., p. 412. 
if Yale Review, Vol. 4, pp. 156-170, “Misunderstandings about economic 
terms.’ 
t Tn a footnote, p. 5.