The next part of the lectures, that dealing with the causes of the slow progress of opulence, forms the foundation for Book III of the Wealth of Nations . The influence of commerce on manners disappears as an independent heading, but most of the matter dealt with under it is utilised in the discussions of education and military organisation.
Besides consumption, two other subjects, stock-jobbing and the Mississippi scheme, which are treated at some length in the lectures, are altogether omitted in the Wealth of Nations . The description of stock-jobbing was probably left out because better suited to the youthful hearers of the lectures than to the maturer readers of the book. The Mississippi scheme was omitted, Smith himself says, because it had been adequately discussed by Du Verney.
Here and there discrepancies may be found between the opinions expressed in the lectures and those expressed in the book. The reasonable and straightforward view of the effects of the corn bounty is replaced by a more recondite though less satisfactory doctrine. The remark as to the inconvenience of regulations on foreign commerce having been alleviated by the fact that they encourage trade with countries from which imported raw materials came and discourage it with those from which manufactured goods came does not reappear in the book. The passage