business affairs. There you must weigh and measure with the utmost
possible precision. You must be for ever watching the several channels
of your expenditure, careful to see that in none does the stream rise
higher than the level at which further expenditure ceases to be
profitable. You will not even engage typists or install a telephone in
your office without weighing up fairly carefully the number of typists
or the number of switches that it is worth your while to have. And in
deciding whether to employ say, five typists, or six, you will not
vaguely lump the services of the whole six typists together, and
consider whether as a whole they are worth to you the wages you must
give them. You will, in the most direct and literal manner, weigh up
the _additional_ benefit you would derive from a sixth typist, and if
that does not seem to you equivalent to her wage, you will not engage
her, however essential it may be to you to have one or two typists in
your office. If on the other hand, the utility of having a sixth
typist seems to you worth much more than her pay, the chances are that
you will be well advised to consider the employment of a seventh. And
so, where you stop employing further typists, the utility to you of
the last one, of the "marginal typist" as it were, is unlikely to
differ greatly from her pay.

Now this is not a fancy picture of some remote abstraction called an
"economic man." Allowing for the over-emphasis which is necessary to
drive home the central point, it is a bald account of the aims and
methods of the actual man of business. To ascertain the margin of
profitable expenditure in each direction, to go thus and no further,
is the very essence of the business spirit, as the business man
himself conceives it. When he condemns the extravagance of Government
departments, it is their lack of just this marginal sense that he
chiefly has in mind. "The lore of nicely calculated less or more" may