152 ECONOMIC ESSAYS IN HONOR OF JOHN BATES CLARK 
with the unfortunate result that his unified conception is con- 
verted into the dualistic conception already foreshadowed by 
Hadley. This is the passage: * 
Capital is a fund and income a flow. This difference between capital 
and income is, however, not the only one. There is another important 
difference, namely, that capital is wealth, and income is the service 
of wealth. We have, therefore, the following definitions: A stock of 
wealth existing at an wnstant of time is called capital. A flow of 
services through a period of time is called income. 
Now it must be said of these dualistic definitions that they are 
quite useless for the purpose in view. Fisher's own work on 
capital and income deals mainly with financial conceptions 
untouched in these definitions, incomes as price-quanta, dis- 
counted and summed up in capital (also a price quantum) con- 
ceived of as the present worth of claims to future monetary 
incomes, no matter whence or how derived (even from intangible 
rights). And the definitions are at least in part tautological, 
for while it would be logically possible (even though theoretically 
useless) to have a fund of wealth (material goods) and to con- 
trast it with a flow of the same goods, it is not possible to con- 
ceive of a literal stock of services at an instant of time; it is 
possible only to conceive of their present worth as a financial 
fund at an instant of time. Services (taken in the sense of uses 
either of wealth or of human beings) may conceivably be delayed 
or hastened, but they are in their very nature a flow; they cannot 
be heaped up and constitute a stock of services. They can at 
most, as they occur, be “incorporated” in durable forms of wealth. 
If this is so, then why this elaborate contrast between a flow of 
services and a fund of something quite different? It is the 
vestigial remains of the older conception that Fisher has been 
obliged to discard. 
The idea of a “fund” as a financial sum, estimate, or valuation, 
at an instant of time, has become confused with the idea of a 
“fund” as a heap or store of physical goods existing at an instant 
of time. The phrases of Fisher's definitions form a superficial, 
verbal bond of connection between the old conception and the new 
one, while in fact the essential distinction has become that not 
between income as a flow and capital as a fund (of the “very 
same” material things) but that between a valuation of services 
L The Nature of Capital and Income (1906), p. 52. Italics in the original.