132 NATURE OF CAPITAL AND INCOME [Cmar. VIII

much income or outgo comes from ‘cash’ we need only
follow the well-established usage of bookkeepers which
regards a stock of cash as though it were a gold mine
which, consequently, is to be credited with all the gold or
cash which comes out of it, and debited with all that goes
into it. This usage often puzzles the novice, but its correctness
 is undoubted and it harmonizes with our definition
 of services and disservices. For the services or
desirable events which come from one’s stock of cash —
the events, in fact, for the sake of which that stock of
cash exists — are the furnishing of money from time to
time; the disservices, or the undesirable events occasioned
by that stock of cash, are the absorption by it of money
from time to time. In other words, my purse serves me
whenever it pays my bills; it costs me whenever I, so to
speak, pay its bills. In this respect it is precisely similar
to any other stock of wealth. A bin of coal serves its owner
when it renders him fuel; it costs him when it has to be
filled. The cost may be the sacrifice of money, of labor, or
of coal taken from some other store of coal. In the case
before us, the income from “cash,” or all the payments the
lawyer takes out of his pocket-book or check book, amounts,
let us say, to $3780, whereas the outgo to “cash” — all
sums paid to it — amounts to $4000, leaving $220 as a
net outgo.
The claim on the servants, like the lease of the house,
involves an obligation to pay as well as a right to receive.
We shall suppose that the servants render services during
the month worth $100, and also cost $100 in wages, leaving
 no net balance. Similarly the office clerks cost $500
in wages and yield $500 worth of assistance to the lawyer
in the preparation of his cases.
The man himself receives from his practice during the
month $2000. But his office and professional expenses
amount to $500 and leave a balance of $1500. The class
called “ete.” comprises all sources of income not other-