When Hume received from Dr. Birch Forbes’s Manuscripts and Murdin’s State-papers, in great haste he writes to his brother historian:—­“What I wrote you with regard to Mary, &c., was from the printed histories and papers.  But I am now sorry to tell you that by Murdin’s State-papers, the matter is put beyond all question.  I got these papers during the holidays by Dr. Birch’s means; and as soon as I read them I ran to Millar, and desired him very earnestly to stop the publication of your history till I should write to you, and give you an opportunity of correcting a mistake so important; but he absolutely refused compliance.  He said that your book was now finished; that the whole narrative of Mary’s trial must be wrote over again; that it was uncertain whether the new narrative could be brought within the same compass with the old:  that this change would require the cancelling a great many sheets; that there were scattered passages through the volumes founded on your theory.” What an interview was this of Andrew Millar and David Hume! truly the bibliopole shone to greater advantage than the two theoretical historians!  And so the world had, and eagerly received, what this critical bookseller declared “required the new printing (that is, the new writing) of a great part of the edition!”

When this successful history of Scotland invited Robertson to pursue this newly-discovered province of philosophical or theoretical history, he was long irresolute in his designs, and so unpractised in those researches he was desirous of attempting, that his admirers would have lost his popular productions, had not a fortunate introduction to Dr. Birch, whose life had been spent in historical pursuits, enabled the Scottish historian to open many a clasped book, and to drink of many a sealed fountain.  Robertson was long undecided whether to write the history of Greece, of Leo X., that of William III. and Queen Anne, or that of Charles V., and perhaps many other subjects.

We have a curious letter of Lord Orford’s, detailing the purport of a visit Robertson paid to him to inquire after materials for the reigns of William and Anne; he seemed to have little other knowledge than what he had taken upon trust.  “I painted to him,” says Lord Orford, “the difficulties and the want of materials—­but the booksellers will out-argue me.”  Both the historian and “the booksellers” had resolved on another history:  and Robertson looked upon it as a task which he wished to have set to him, and not a glorious toil long matured in his mind.  But how did he come prepared to the very dissimilar subjects he proposed?  When he resolved to write the history of Charles V., he confesses to Dr. Birch:  “I never had access to any copious libraries, and do not pretend to any extensive knowledge of authors; but I have made a list of such as I thought most essential to the subject, and have put them down as I found them mentioned in any book I happened to read.