||Sefer ha-Middot or Musar Haskel, a collection of essays on the essence of the soul and its faculties. The work reflects contemporary philosophical and ethical German thought. Sefer ha-Middot became popular among learned Jews in Eastern Europe.
Naphtali Herz Wessely (Hartwig; 1725–1805), was an important member of the German Haskalah. Wessely's ancestors had fled Poland during the Chmielnicki pogroms and settled in Wesel on the Rhine from where the family took its name. Born in Hamburg, Wessely spent his childhood in Copenhagen where his father was a purveyor to the king of Denmark. He received his religious education at the yeshivah of Jonathan Eybeschuetz, who influenced him greatly, and read literature and scientific works in a number of European languages, Associated with the Feitel Bank, Wessely's business affairs took him to Amsterdam and Berlin. In Berlin he met Moses Mendelssohn and contributed a commentary on Leviticus (Berlin, 1782) to the Biur.