AT DIFFERENT PERIODS. 89 
bour. For instance, if A and B were each pro- 
duced by six days’ labour, they would be equal 
in value; but if A should from some cause or 
other require 12 days’ labour, then the value of 
A would be to the value of B as 12 to 6. But 
suppose that a in 1810 required six days’ la- 
bour at 4s., making 24s., and in 1811, 6 days at 
6s., making 36s., if the value of the commodity 
was 40s. at the former period, it would still be 
40s. at the latter. And suppose that Bin 1810 
required 3 days’ labour at 4s., making 12s., and 
in 1811, 3 days’ labour at 6s., making 18s., the 
value of the commodity at each period would 
be 20s. 
Now this author's argument is, that because a 
and B at these two periods do not vary in value 
with the varying value of labour, therefore they 
are not to each other in value as the values of 
the producing labour. But itis evident that 40s., 
the value of 4 in 1810, is to 20s., the value of 
B at the same period, as 24s., the value of the 
producing labour in a, is to 12s., the value of