Leonhard Eulers letters to a German princess : a milestone in the history of physics textbooks and more Leonhard Eulers Letters to a German Princess on Various Subjects in Physics and Philosophy is a milestone in the history of physics textbooks and the instruction of women in the sciences. It also covers views of its author on epistemology religion and innovations in scientific equipment including telescopes and microscopes. Today 250 years later we study this work of Eulers as a foundation for the history of physics teaching and analyze the letters from an historical and pedagogical point of view.