The differences of opinion among political economists have of late been a frequent subject of complaint; and it must be allowed, that one of the principal causes of them may be traced to the different meanings in which the same terms have been used by different writers.
The object of the present publication is, to draw attention to an obstacle in the study of political economy, which has now increased to no inconsiderable magnitude. But this could not be done merely by laying down rules for the definition and application of terms, and defining conformably
to them. It was necessary to show the difficulties which had resulted from an inattention to this subject, in some of the most popular works on political economy; and this has naturally led to the discussion of certain important principles and questions of classification, which it would be most desirable to settle previously, as the only foundation for a correct definition and application of terms.
These are the reasons for the arrangement and mode of treating the subject which has been adopted.