James Boswell's uncle John was a member of a sect known as the Glasites.
Johann Friedrich Wilhelm JerusalemBorn 1709
Son of Theodor Wilhelm Jerusalem. Married (1742) to Martha Christina Pfeiffer, with whom he had several children.
Jerusalem was a student of Theology at Leipzig (1727-1731); among his teachers were Johann Gottlieb Carpzov and Johann Christoph Gottsched, who introduced him to Wolfian philosophy. He graduated from the University of Wittenberg on April 29, 1731. In 1742, he was hired by Karl I to become a tutor to the hereditary prince of the duchy of Brunswick-Lüneburg-Wolfenbüttel (presumably Karl Wilhelm Ferdinand), and he was to remain in the service of that reigning family until his death. In 1745 he co-founded the Collegium Carolinum.
Life with Boswell:
Boswell met Jerusalem at Brunswick on June 28, 1764, delivering a letter to him from Count Bentinck. Boswell "found him a learned, agreeable man with a pleasing simplicity of manners.". They had a long discussion about religion, and it is remarked in the notes to GT1 that "[Jerusalem] preached a new kind of 'clear Christianity' which Boswell at this stage of his religious progress would naturally have found interesting.".
They had a long conversation on August 11, 1764, during Boswell's second visit to Brunswick, and again on August 15.
Several of Jerusalem's writings can be acquired via the AbeBooks.com used books search engine, although none of his works seems to have been translated from German.