that the costs and future benefits of the undertaking can be estimated
accurately; and that the problem reduces itself to one of expending
now a sum, let us say, of $100,000,000, with the prospects of
obtaining in the future an income of power, or whatever it may be,
worth $5,000,000 per annum. I have assumed for the sake of simplicity
that we shall still be reckoning in terms of money, though possibly
the executive may have substituted Marxian labor units; but it is
quite immaterial to the present argument what the measuring rod may
be. The point to be observed is, that it is impossible to tackle the
problem at all without the conception of a rate of interest. For
suppose that you tried to do without it, and said, "We shall take a
long view. The interests of the future are no less our concern than
those of the present; we shall not discriminate between them. We shall
regard as an enterprise worthy to be undertaken whatever promises to
yield in the course of time a return larger than the outlay." Where
will this lead you? The particular proposal set out above would
clearly pass the test; for in twenty years the resultant benefits
would have added up to a figure equivalent to the initial cost. But
equally clearly, the cost might have been more than $100,000,000; it
might have been $250,000,000, $500,000,000, whatever figure you care
to take, and if you extend the period similarly to fifty or one
hundred years, sooner or later the gains would top the cost. Now there
is no limit to the enterprises which would pay their way on this
basis; and it would be quite impossible to undertake them all. For
they would swallow up all and more than all your labor and your
materials, and would leave you with no resources with which to meet
the recurrent daily wants of men. Clearly, then, in some way or other,
you must pick and choose, you must reject some enterprises as
_insufficiently_ worth while. But how would you proceed to choose?
Without a clear principle, a simple criterion to guide you, you would