Indeed, one of the great merits of Hume's Essays on Political Economy is, that he knows when he is getting out of his depth, and does not conceal his position. With many writers on this subject, the point where clear and satisfactory inquiry ends, is that where dogmatism begins; but Hume stops at that point, sees and admits the difficulty, and acknowledges that he can go no farther with safety. Among these essays there is one which, like the Oceana of Harrington, though on a smaller scale, is an attempt to construct a system of polity. It is called "Idea of a Perfect Commonwealth." The system so put together is liable to practical objections at every step, and is utterly destitute of that sagacious applicability to the transactions of real business, for which the efforts in hypothetical legislation by Bentham are distinguished.[361:1] Another essay of a different character is conspicuous for the vast extent of the learning and research which must have been expended in bringing together its crowd of apt illustrations,--that on "The Populousness of Ancient Nations." To afford a choice of so many applicable facts, directly bearing on the point, how wide must have been the research, how extensive the rejection of such fruit of that research, as did not answer his purpose! In the perusal of this essay one is inclined to regret that Hume afterwards made a portion of modern Europe the object of his historical labours, instead of taking up some department of the history of classical antiquity. The full blown lustre of Greek and Roman greatness had far more of his sympathy than the history of his own countrymen, and their slow progress from barbarism to civilisation. The materials were nearly all confined to the great spirits of antiquity, with whom he delighted to hold converse, instead of involving that heap of documentary matter with which the historian of Britain must grapple; acts of parliament, journals, writs, legal documents, &c.--all things which his soul abhorred. In such a field he might have escaped the imputation of not being a full and fair investigator; and he would, at all events, have avoided the reproach thrown on him by the prying antiquary, who, by the light of newly discovered documents, could charge him with having neglected that of which he did not, and could not, know the existence.[364:1]