Gauß and Dirichlet -- an episode (Q2855699)

It is well known that Gauss produced eight proofs of the reciprocity law, which was his ``fundamental theorem''. The author's subject is the quadratic reciprocity law, which was investigated not only by Gauss in 1825 but also by other mathematicians during the years 1820 and 1850. One of them was Gustav Lejeune Dirichlet, who had studied in Paris. On May 1826, Dirichlet wrote a letter to Gauss asking him for support, because he was investigating the Fermat problem. Gauss was immediately fascinated by the ideas of the young man and granted the support. So Dirichlet became professor in Breslau. In 1828, Dirichlet had finished a paper concerning the quadratic reciprocity law. On May 30, 1828, Gauss answered and gave acknowledgement to Dirichlet's merits. Dirichlet and Gauss met each other in September 1828 in Berlin, and in the future it was Berlin where Dirichlet made his way up. In 1831, Gauss' \textit{Commentatio secunda} was announced which appeared a year later. But it was Dirichlet and not Gauss who published the first ideas for a proof of the biquadratic reciprocity law; the first complete proof was published by Eisenstein in 1844. This is a well-written article in which a very interesting ``episode'' is reported.