Now, Adam Smith was inquiring into the nature and causes of the wealth of nations; and having confined the term _wealth_ to material objects, and described human labour as the main source of wealth, he clearly saw the necessity of making some distinction between those different kinds of labour which, without reference to their utility, he could not but observe had the most essentially distinct effects, in directly causing that wealth, the nature of which he was investigating. He called one of these kinds of labour _productive_, or productive of wealth, and the other _unproductive_, or not productive of wealth; and knowing that it would occasion interminable confusion, and break down all the barriers between production and consumption, to attempt to estimate the circumstances which might _indirectly_ contribute to the production of wealth, he described productive labour in such a way, as to leave no doubt that he meant the labour which was so directly productive of wealth, as to be estimated in the quantity or value of the material object produced. In his application of the terms _productive_ and _unproductive_, therefore, he does not seem to have violated the usage of common conversation and writing; and it appears to me, that, if we fully and impartially consider the consequences of making no distinction between different kinds of labour, we must feel the conviction that the terms which he has adopted are pre-eminently useful for the purpose to which they are applied—that is, to enable him to explain, intelligibly and satisfactorily, the causes of the wealth of different nations, according to the ordinary meaning which men attach to the term wealth, whatever may be their theories on the subject.