cleared up what had before been an 'impenetrable mystery,' and
showed the true relations of profit, wages, and prices.[321] Ricardo's
theory of value, again, was a starting-point of the chief modern
Socialist theories. It marked, as has been said,[322] the point at
which the doctrine of the rights of man changes from a purely
political to an economical theory. Ricardo remarks in his first
chapter that the vagueness of theories of value has been the most
fertile source of economic errors. He admitted to the end of his life
that he had not fully cleared up the difficulty. Modern economists
have refuted and revised and discussed, and, let us hope, now made
everything quite plain. They have certainly shown that some of
Ricardo's puzzles implied confusions singular in so keen a thinker.
That may serve as a warning against dogmatism. Boys in the next
generation will probably be asked by examiners to expose the palpable
fallacies of what to us seem to be demonstrable truths. At any rate,
I must try to indicate the critical point as briefly as possible.

The word 'value,' in the first place, has varying meanings, which give
an opportunity for writers of text-books to exhibit their powers of
lucid exposition. The value of a thing in one sense is what it will
fetch; the quantity of some other thing for which it is actually
exchanged in the market. In that sense, as Ricardo incidentally
observes,[323] the word becomes meaningless unless you can say what is
the other thing. It is self-contradictory to speak as if a thing by
itself could have a constant or any value. Value, however, may take a
different sense. It is the economic equivalent of the 'utility' of
Bentham's 'felicific calculus.' It means the 'lot of pleasure' which
causes a thing to be desirable. If we could tell how many units of
utility it contained we could infer the rate of exchange for other
things. The value of anything 'in use' will correspond to the number
of units of utility which it contains; and things which have the same
quantity of 'utilities' will have the same 'exchangeable value.'
Ricardo can thus consider the old problem of finding 'an invariable
measure of value.' He points out the difficulty of finding any
particular thing which will serve the purpose, inasmuch as the
relations of everything to everything else are constantly varying. He
therefore proposes to make use of an imaginary measure. If gold were
always produced under exactly the same circumst