E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
It appears from the Journal of George Fox, who was imprisoned for nearly twelve months in Derby, that the Quakers first obtained the appellation (1650) by which they are now known from the following circumstance:Justice Bennet, of Derby, says Fox, was the first to call us Quakers, because I bade him quake and tremble at the word of the Lord. The system of the Quakers is laid down by Robert Barclay in fifteen theses, called Barclays Apology, addressed to Charles II.