AT DIFFERENT PERIODS. 75

itself, He distinctly states, that if equal quantities
 of gold could always be obtained by
equal quantities of labour, the value of gold
“ would be invariable, and it would be eminently
 well calculated to measure the varying
value of all other things,” whence it follows,
that this invariableness must be intended to be
affirmed of the value of gold compared with
itself, and not of any relation between gold
and some other commodity.
The same remarks apply to all attempts to
find out something of invariable value. Adam
Smith and Mr. Malthus, in considering labour
alone as never varying in its own value, assert
by implication, that labour at one period may
be compared in value with labour at another
period, without reference to any other thing
whatever*. I fully concede that such a notion

* For further instances see Wealth of Nations, Book i,
Chap. v, and Mr. Malthus’s Pamphlet on the Measure of
Value, p. 24 and 25. When we come to treat on the measurement
 of value, we shall find this notion at the bottom
of some important errors on that subject.