In 1764 he alluded gracefully to the connection between Hanover and England in a piece upon the birthday of Queen Charlotte, and having been promoted secretary of the University Library at Goettingen, the young savant commenced a translation of Leibniz's philosophical works which was issued in Latin and French after the original MSS.

in the Royal Library at Hanover, with a preface by Raspe's old college friend Kaestner (Goettingen, 1765).

At once a courtier, an antiquary, and a philosopher, Raspe next sought to display his vocation for polite letters, by publishing an ambitious allegorical poem of the age of chivalry, entitled "Hermin and Gunilde," which was not only exceedingly well reviewed, but received the honour of a parody entitled "Harlequin and Columbine." He also wrote translations of several of the poems of Ossian, and a disquisition upon their genuineness; and then with better inspiration he wrote a considerable treatise on "Percy's Reliques of Ancient Poetry," with metrical translations, being thus the first to call the attention of Germany to these admirable poems, which were afterwards so successfully ransacked by Buerger, Herder, and other early German romanticists.
In 1767 Raspe was again advanced by being appointed Professor at the Collegium Carolinum in Cassel, and keeper of the landgrave of Hesse's rich and curious collection of antique gems and medals.

He was shortly afterwards appointed Librarian in the same city, and in 1771 he married.
He continued writing on natural history, mineralogy, and archaeology, and in 1769 a paper in the 59th volume of the Philosophical Transactions, on the bones and teeth of elephants and other animals found in North America and various boreal regions of the world, procured his election as an honorary member of the Royal Society of London.

His conclusion in this paper that large elephants or mammoths must have previously existed in boreal regions has, of course, been abundantly justified by later investigations.