“It is indeed evident,” he wrote in Of Money, “that money is
nothing but the representation of labour and commodities, and serves only
as a method of rating or estimating them. Where coin is in greater plenty, as
a greater quantity of it is required to represent the same quantity of goods, it
can have no effect, either good or bad...any more than it would make an alteration on a merchant’s books, if, instead of the Arabian method of notation,
which requires few characters, he should make use of the Roman, which
requires a great many.” (p.28)1
He returns to this idea that changes in the quantity of money are just units