The next ten years of his life, after his arrival from the continent, Mr. Smith passed with his mother at Kirkaldy, though he occasionally, during that time, visited London and Edinburgh. Mr. Hume, who considered a town as the proper scene for a man of letters, made many attempts to prevail on him to leave his retirement. At length, in the beginning of the year 1776, Mr. Smith accounted to the world for his long retreat, by the publication of his 'Inquiry into the Nature and Causes of the Wealth of Nations.' This work chiefly comprehended the subject of the fourth and last division of his lectures, namely, those political regulations that have their origin in expediency. For about twenty years of his life, his attention had been chiefly devoted to the study of subjects connected with the science of political economy. His long residence in the mercantile city of Glasgow afforded him opportunities of deriving information, in many particulars, from the best sources; his travels on the continent contributed to extend his knowledge, and correct many of those misapprehensions of life and manners which the best descriptions of them are found to convey; and the intimacy in which he lived with some of the leaders of the sect of economists, and other writers on the subject of political economy, could not fail to assist him in methodizing his speculations, and of adding to the soundness of his conclusions.--After his arrival in this country, he wanted nothing more than leisure, to arrange his materials, and prepare them for publication: and for this purpose he passed in retirement the subsequent ten years. The great aim of Mr. Smith's Inquiry, the fruit of so much research, and the work of so many years, is, as Professor Stewart observes, to direct the policy of nations with respect to one most important class of its laws,--those which form its system of political economy: 'and he has unquestionably,' the same eloquent writer adds, 'had the merit of presenting to the world the most comprehensive and perfect work that has yet appeared on the general principles of any branch of legislation.' 'A great and leading object of Mr. Smith's speculations,' as Mr. Stewart also observes, 'is to demonstrate, that the most effectual plan for advancing a people to greatness, is to maintain that order of things which nature has pointed out, by allowing every man, as long as he observes the rules of justice, to pursue his own interest in his own way, and to bring both his industry and his capital into the freest competition with these of his fellow citizens.'