AT DIFFERENT PERIODS. 73

another period ; but a comparison of ratios, or
a comparison of the relative quantities in which
commodities exchanged for each other at two
different epochs. If a commodity of in the
year 100 was worth 2 B, and in 1800 was
worth 4 B, we should say that a had doubled
its value to B. But this, which is the only kind
of comparison we can institute, would not give
us any relation between A in 100 and A in
1800; it would be simply a comparison of the
relation between A and Bin each of those years.
It is impossible for a direct relation of value
to exist between A in 100 and 4 in 1800, just
as it is impossible for the relation of distance
to exist between the sun at the former period
and the sun at the latter. This perhaps will be
still more apparent if we make use of the definition
 of value instead of the term. It will at
once be seen how absurd it would be to talk
of the power of 4 in the year 100, to command
in exchange the same commodity in 1800.
It may, perhaps, be alleged, that I am here
fighting with a mere shadow of my own crea-