at present for the death of Baron Mure, which is an irreparable loss to our society.  He was among the oldest and best friends I had in the world.[245]

On the same day as Hume wrote this letter from Edinburgh, Gibbon wrote from London to Adam Ferguson and said among other things, “What an excellent work is that with which our common friend Mr. Adam Smith has enriched the public!  An extensive science in a single book, and the most profound ideas expressed in the most perspicuous language.  He proposes visiting you very soon, and I find he means to exert his most strenuous endeavours to persuade Mr. Hume to return with him to town.  I am sorry to hear that the health and spirits of that truly great man are in a less favourable state than his friends could wish, and I am sure you will join your efforts in convincing him of the benefits of exercise, dissipation, and change of air.”

Some of Smith’s personal friends seem to have entertained the common prejudice that a good work on commerce could not be reasonably expected from a man who had never been engaged in any branch of practical business, and seemed in outward air and appearance so ill fitted to succeed in such a line of business if he had engaged in it.  One of these was Sir John Pringle, President of the Royal Society, and formerly, like Smith himself, Professor of Moral Philosophy at a Scotch university.  When the Wealth of Nations appeared Sir John Pringle remarked to Boswell that Smith, having never been in trade, could not be expected to write well on that subject any more than a lawyer upon physic, and Boswell repeated the remark to Johnson, who at once, however, sent it to the winds.  “He is mistaken, sir,” said the Doctor; “a man who has never been engaged in trade himself may undoubtedly write well upon trade, and there is nothing that requires more to be illustrated by philosophy than does trade.  As to mere wealth—­that is to say, money—­it is clear that one nation or one individual cannot increase its store but by making another poorer; but trade procures what is more valuable, the reciprocation of the peculiar advantages of different countries.  A merchant seldom thinks but of his own particular trade.  To write a good book upon it a man must have extensive views; it is not necessary to have practised to write well upon a subject.”

It is not within the scope of a work like the present to give an account of the doctrines of the Wealth of Nations, or any estimate of their originality or value, or of their influence on the progress of science, on the policy and prosperity of nations, or on the practical happiness of mankind.  Buckle, as we know, declared it to be “in its ultimate results probably the most important book that has ever been written”; a book, he said, which has “done more towards the happiness of man than has been effected by the united abilities of all the statesmen and legislators of whom history has preserved an authentic account";[246] and even those who take the most sober view of the place of this work in history readily admit that its public career, which is far from being ended yet, is a very remarkable story of successive conquest.