Tassie engaged Raspe in 1785 to take charge of his cabinets, and to commence describing their contents: he can hardly have been ignorant of his employé's delinquencies in the past, but he probably estimated that mere casts of gems would not offer sufficient temptation to a man of Raspe's eclectic tastes to make the experiment a dangerous one. Early in 1786, Raspe produced a brief but well-executed conspectus of the arrangement and classification of the collection, and this was followed in 1791 by "A Descriptive Catalogue," in which over fifteen thousand casts of ancient and modern engraved gems, cameos, and intaglios from the most renowned cabinets in Europe were enumerated and described in French and English. The two quarto volumes are a monument of patient and highly skilled industry, and they still fetch high prices. The elaborate introduction prefixed to the work was dated from Edinburgh, April 16, 1790.

This laborious task completed, Raspe lost no time in applying himself with renewed energy to mineralogical work. It was announced in the Scots Magazine for October 1791 that he had discovered in the extreme north of Scotland, where he had been invited to search for minerals, copper, lead, iron, manganese, and other valuable products of a similar character. From Sutherland he brought specimens of the finest clay, and reported a fine vein of heavy spar and "every symptom of coal." But in Caithness lay the loadstone which had brought Raspe to Scotland. This was no other than Sir John Sinclair of Ulbster, a benevolent gentleman of an ingenious and inquiring disposition, who was anxious to exploit the supposed mineral wealth of his barren Scottish possessions. With him Raspe took up his abode for a considerable time at his spray-beaten castle on the Pentland Firth, and there is a tradition, among members of the family, of Sir John's unfailing appreciation of the wide intelligence and facetious humour of Raspe's conversation. Sinclair had some years previously discovered a small vein of yellow mundick on the moor of Skinnet, four miles from Thurso. The Cornish miners he consulted told him that the mundick was itself of no value, but a good sign of the proximity of other valuable minerals. Mundick, said they, was a good horseman, and always rode on a good load. He now employed Raspe to examine the ground, not designing to mine it himself, but to let it out to other capitalists in return for a royalty, should the investigation justify his hopes. The necessary funds were put at Raspe's disposal, and masses of bright, heavy material were brought to Thurso Castle as a foretaste of what was coming. But when the time came for the fruition of this golden promise, Raspe disappeared, and subsequent inquiries revealed the deplorable fact that these opulent ores had been carefully imported by the mining expert from Cornwall, and planted in the places where they were found. Sir Walter Scott must have had the incident (though not Raspe) in his mind when he created the Dousterswivel of his "Antiquary." As for Raspe, he betook himself to a remote part of the United Kingdom, and had commenced some mining operations in country Donegal, when he was carried off by scarlet fever at Muckross in 1794. Such in brief outline was the career of Rudolph Erich Raspe, scholar, swindler, and undoubted creator of Baron Munchausen.

The merit of Munchausen, as the adult reader will readily perceive, does not reside in its literary style, for Raspe is no exception to the rule that a man never has a style worthy of the name in a language that he did not prattle in. But it is equally obvious that the real and original Munchausen, as Raspe conceived and doubtless intended at one time to develop him, was a delightful personage whom it would be the height of absurdity to designate a mere liar. Unfortunately the task was taken out of his hand and a good character spoiled, like many another, by mere sequel-mongers. Raspe was an impudent scoundrel, and fortunately so; his impudence relieves us of any difficulty in resolving the question,—to whom (if any one) did he owe the original conception of the character whose fame is now so universal.

When Raspe was resident in Göttingen he obtained, in all probability through Gerlach Adolph von Munchausen, the great patron of arts and letters and of Göttingen University, an introduction to Hieronynimus Karl Friedrich von Munchausen, at whose hospitable mansion at Bodenwerder he became an occasional visitor. Hieronynimus, who was born at Bodenwerder on May 11, 1720, was a cadet of what was known as the black line of the house of Rinteln Bodenwerder, and in his youth served as a page in the service of Prince Anton Ulrich of Brunswick. When quite a stripling he obtained a cornetcy in the "Brunswick Regiment" in the Russian service, and on November 27, 1740, he was created a lieutenant by letters patent of the Empress Anna, and served two arduous campaigns against the Turks during the following years. In 1750 he was promoted to be a captain of cuirassiers by the Empress Elizabeth, and about 1760 he retired from the Russian service to live upon his patrimonial estate at Bodenwerder in the congenial society of his wife and his paragon among huntsmen, Rösemeyer, for whose particular benefit he maintained a fine pack of hounds. He kept open house, and loved to divert his guests with stories, not in the braggart vein of Dugald Dalgetty, but so embellished with palpably extravagant lies as to crack with a humour that was all their own. The manner has been appropriated by Artemus Ward and Mark Twain, but it was invented by Munchausen. Now the stories mainly relate to sporting adventures, and it has been asserted by one contemporary of the baron that Munchausen contracted the habit of drawing such a long-bow as a measure of self-defence against his invaluable but loquacious henchman, the worthy Rösemeyer. But it is more probable, as is hinted in the first preface, that Munchausen, being a shrewd man, found the practice a sovereign specific against bores and all other kinds of serious or irrelevant people, while it naturally endeared him to the friends of whom he had no small number.

He told his stories with imperturbable sang froid, in a dry manner, and with perfect naturalness and simplicity. He spoke as a man of the world, without circumlocution; his adventures were numerous and perhaps singular, but only such as might have been expected to happen to a man of so much experience. A smile never traversed his face as he related the least credible of his tales, which the less intimate of his acquaintance began in time to think he meant to be taken seriously. In short, so strangely entertaining were both manner and matter of his narratives, that "Munchausen's Stories" became a by-word among a host of appreciative acquaintance. Among these was Raspe, who years afterwards, when he was starving in London, bethought himself of the incomparable baron.