Poor Latin nearly kept Dirichlet, a founder of analytic number theory, out of academia
Gustav Lejeune Dirichlet never mastered Latin, and it dogged him for decades. It cost him his school leaving exam, forced Bonn to hand him an honorary doctorate instead of a normal one, and let him delay a required Latin lecture in Berlin for twenty years, all while he reshaped number theory.
Düren, a Rhineland town then under French rule, was where he arrived on 13 February 1805 as the youngest of seven children of the local postmaster. The odd surname means the young man from Richelette, the Belgian village near Liège his grandfather came from. His parents hoped he would become a merchant, then a lawyer, but he talked them round twice. In Cologne he took lessons from Georg Ohm.
With German universities offering little advanced mathematics, he went to Paris in May 1822, carrying Gauss's Disquisitiones Arithmeticae, a book he kept by him all his life. A job teaching German to General Foy's children made him self-supporting. His partial proof of Fermat's Last Theorem for fifth powers was the first progress on the problem since Euler, and in June 1825, aged twenty and without a degree, he presented it to the French Academy. Legendre, a referee, finished the case first, and Dirichlet soon after.
When Foy died, Alexander von Humboldt, who wanted Berlin to become a scientific capital, lobbied for him and won a rare burst of praise from Gauss. Dirichlet taught at Breslau, then from 1828 at Berlin's Military Academy, where he brought calculus into the syllabus. In 1832 he became the youngest member of the Prussian Academy at 27 and married Rebecka Mendelssohn, younger sister of Felix and Fanny, whom he met at her family's weekly salon.
He was the first German professor to lecture on number theory, and his doctoral students included Leopold Kronecker and Gotthold Eisenstein. A close friend of Carl Jacobi, he nursed him through illness and accompanied him to Italy in 1843. Liberal in politics, he backed the 1848 revolution and stood guard with a rifle outside the Prince of Prussia's palace, after which some newspapers branded him part of the red contingent. He died in 1859.
Source: Peter Gustav Lejeune Dirichlet
