In 1788, Friesenhausen moved to Berlin where he lived for the next eight years and was supported by Benjamin Halberstat. Berlin at that time was the center of the haskala movement (Jewish Enlightenment). Despite his involvement in secular subjects, Friesenhausen continued to study Torah intensively. In 1796, Friesenhausen published his first book, Kelil Heshbon a Hebrew language manual on algebra and trigonometry. Thereafter, Friesenhausen left Berlin to travel throughout Europe for the dual purpose of selling his newly published book and to attain advance subscriptions for planned book, Mosodot Tevel.
