In offering to the public a new edition of some lectures delivered in Dublin more than seventeen years ago, a few words of explanation are needed. As regards the substance of the opinions advanced—the view taken of Political Economy and of its methods of proof and development—the present work does not differ from its predecessor; but extensive changes have been made in the form and treatment. Numerous passages have been recast; increased prominence has been given to aspects of the case only touched on in the former volume; and some entirely new topics have been introduced. To one of these—’Definition’—an additional lecture has been devoted. I would fain hope that in its new shape the work will be found somewhat less unworthy than in its earlier form of such favour as it has met with. No one, however, can be more conscious than the author how very far it still falls short of what such a work ought to be…. [From the Preface to the Second Edition.]