here the words productive and unproductive have been affected with
additional ambiguities, corresponding to the different extension which
different writers have given to the term wealth.

Some have given the name of wealth to _all things_ which tend to the use
or enjoyment of mankind, and which possess exchangeable value. This last
clause is added to exclude air, the light of the sun, and any other
things which can be obtained in unlimited quantity without labour or
sacrifice; together with all such things as, though produced by labour,
are not held in sufficient general estimation to command any price in
the market.

But when this definition came to be explained, many persons were
disposed to interpret "_all things_ which tend to the use or enjoyment
of man," as implying only all _material_ things. _Immaterial_ products
they refused to consider as wealth; and labour or expenditure which
yielded nothing but immaterial products, they characterised as
unproductive labour and unproductive expenditure.

To this it was, or might have been, answered, that according to this
classification, a carpenter's labour at his trade is productive labour,
but the same individual's labour in learning his trade was unproductive
labour. Yet it is obvious that, on both occasions, his labour tended
exclusively to what is allowed to be production: the one was equally
indispensable with the other, to the ultimate result. Further, if we
adopted the above definition, we should be obliged to say that a nation
whose artisans were twice as skilful as those of another nation, was
not, _ceteris paribus_, more wealthy; although it is evident that every
one of the results of wealth, and everything for the sake of which
wealth is desired, would be possessed by the former country in a higher