" Frederick II of Prussia (known as “the Great,” reigned 1740–1786) famously ran his Berlin court—and the associated Academy of Sciences—in French. When Voltaire visited in 1750, he wrote to the Marquis de Thibouville that “I find myself here in France. One speaks only our language. German is for the soldiers and for the horses; it is only necessary on the road.”187f "

― Michael D. Gordin , Scientific Babel: How Science Was Done Before and After Global English