ate trade-marks and brands, if honestly used, become a prominent
element in exchange. These are protected rightly by being filed with the
government, which secures to the originator his sole use of such a proof
of quality.

In some articles of trade, when a whole community is interested, the
government goes further and undertakes inspection and branding by an
official. This in most states applies to kerosene oil, first for public
safety, but afterwards for protection of exchange. Laws regulating the
quality of fertilizers are based upon the necessity of knowledge, that
bargains may be fair; and in many parts of our country now the branding of
ground feeds, with an analysis of their qualities, is deemed an essential
of safe bargaining. The extent to which this effort to establish the
certainty of qualities may need to be carried can be estimated by the
recent agitation over adulterations of food products. All believe that, as
buyers, they have a right to know the quality of what they buy. It is
conceivable that markets may some time establish a system of terms,
descriptive of qualities, almost as definite as weights and measures. All
this contributes to fair competition in exchange.

_Standards of value._--More important still in the machinery of exchange is
a standard unit of value. We have seen that value in any article of
commerce can be fixed in terms of any other article, but prices remain
indefinite so long as there is want of universal appreciation or appraisal
in essentially the same terms and ideas. The tendency toward definite
prices in well understood units of value is as clearly perceptible in the
progress of commerce as is the tendency toward definiteness in weights and
measures.

In early ages almost any article of common use, so that its qualities
might be generally understood, has served as a standard of value, in terms
of which all wealth has been estimated. Communities engaged in grazing
counted all their wealth by cattle. Homer's heroes wore armor valued in
cattle, and early Roman coins bore the images of cattle, while the very
name of Roman coins, _pecunia_, is supposed to have been derived from the
name of the flock. Communities of fishermen for a long period have
estimated wealth in dried fish. More mechanical peoples have used some
article of manufacture, like nails in some Scottish villages and the
country cloth of western Africa. Sometimes a single prime article of
export has served the purpose