Through this short story I also learned that Fermat's principle is just one example of a variational principle. I'm not an expert, but if I understand it correc

Through this short story I also learned that Fermat's principle is just one example of a variational principle. I'm not an expert, but if I understand it correctly, many physical laws can be restated as variational principles. See e.g. https://en.wikipedia.org/wiki/History_of_variational_principles_in_physics https://en.wikipedia.org/wiki/History_of_variational_princip...