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toit. In either case, if they are steady in their
operation, they may be equally regarded as
causes of value. We may often assign an effect
 to a cause, when perhaps we are unable to
trace the exact series of changes occurring between
 them, or, in other words, the less prominent
 links in the chain of causes and effects
by which they are separated in time, but connected
 in efficiency. In reference to the present
subject, this may be easily illustrated. The
equality in the cost of production of two articles,
 for example, is a cause of their exchanging
for each other. This we know is the general
effect of such circumstances; but it would be
difficult to trace with precision the mode in
which the effect was produced, and which indeed
 might vary on different occasions without
disturbing the result. Suppose two persons, A
and B, of whom the former has linen, which he
wishes to exchange for woollen cloth, and the
latter has woollen cloth, which he wishes to exchange
 for linen. The matter would be abundantly
 plain, if, besides knowing what his own