. For the phenomena of routine and habit are thereby made a
standard by which all others, if indeed recognized as real at all, must
be judged "exceptional." And, as we shall see, to do this introduces
difficulty into certain parts of substantive economic theory.

Again, objection may attach to the view that equivalence of the "salient
members" of the opposing systems is only another name for the
comprehensive fact of the novelty's acceptance. For if we hesitate in
such a case, is this not because we judge the price too high? What can
this signify but that the service or satisfaction we expect from the
novelty falls short of sufficing to convince us? And unless we are
dealing with measured quantities, how can we come to this conclusion?
Moreover, if the novel commodity is divided into units we may take a
smaller quantity when the price demanded is "high" than if the price
were lower. And does this not suggest predetermined value-magnitudes as
data? But if one takes thus a smaller amount, as the argument contends,
it is because there is a presumption of being able to make some
important total use of it and there is no general reason apparent for
supposing that this will be merely a fractional part of a larger but
like significance that might be hoped for from a larger quantity. And on
the other hand, the prospect simply may not tempt at all; the smaller
quantity may be deemed an improbable support for a really promising
total program and the present program will hold its ground, not
seriously shaken. The total demand of a market for a given commodity is
no doubt in some sort a mathematical function of the price. The lower
the price the greater in some ratio will be the number of persons who
will buy and in general the greater the number of units taken by those
who are already buyers. But that such a proposition admits of
statistical proof from the observation of a series of price changes in a
market affords no presumption concerning the nature of the reasons that
move any individual person to his action. The theoretical temptation is
strong, here as elsewhere, in passing from the study of markets to the
personal economy of the individual forthwith to find this also a
trafficking in unit-quantities and marginal satisfactions to which the
concepts and notation of market analysis will readily apply.

It remains to consider certain implications of this view of economic
desire and demand.

II

Sec. 14. It is evident that