Eulero e' chi ha scritto di piu', dopo di lui Cauchy.

Chi ha scritto il meno, ed ha avuto piu' influenza, Galois.

Leonhard Euler (Bale 1707 - Petrograd 1783). Son of a Lutheran minister who had settled at Bale, educated in his native town under the direction of John Bernoulli, with whose sons Daniel and Nicholas he formed a lifelong friendship.

When, in 1725, the younger Bernoullis went to Russia, on the invitation of the empress, they procured a place there for Euler. The severity of the climate aected his eyesight, and in 1735 he lost the use of one eye completely. In 1741 he moved to Berlin at the request, or rather command, of Frederick the Great; here he stayed till 1766, when he returned to Russia, and was succeeded at Berlin by Lagrange. Within two or three years of his going back to Petrograd he became blind; but in spite of this, and although his house, together with many of his papers, were burnt in 1771, he recast and improved most of his earlier works. He died of apoplexy in 1783. He was married twice.

ref: A Short Account of the History of Mathematics

Although Euler's legacy is more than 250 years old, it remains centrally important for mathematicians and physicists and richly deserves the accolade of Pierre-Simon Laplace: "Lisez Euler, Lisez Euler, c'est notre maître à tous." ("Read Euler, read Euler, he is our master in everything.")

ref: The original Euler’s calculus-of-variations method: Key to Lagrangian mechanics for beginners by Jozef Hanca 2004 Technical University, Vysokoskolska 4, 042 00 Kosice, Slovakia

Affine geometry was first recognized by Leonhard Euler in the eighteenth century.

Euler also invented graph theory (Koenigsberg Bridge Problem), seeds of topology (Euler characteristic etc) and so many other things. He is probably the most inspiring mathematician ever, not only because of his theorems and formulas

v-e+f=2, exp(i π)+1=0, 1+1/4+1/9+1/16+...=π2/6 etc,

but also because of his outreach and his passion for making it accessible.

Euler walked the talk, like many of the teachers who throw their energy into the noble cause of teaching. Euler's contributions to algebra pedagogy was not only in writing his textbook in Algebra but producing a gold standard in clarity which is hard to surpass. It is one of the most successful textbooks of all times.

is an important prototype of a mathematics textbook. It appeared first in 1767/1768 in russian. A french translation with an addition of Lagrange appears 1794. The book starts with elementary algebra operations and finishes with a proof of the Fermat conjecture in the case n=3. Legend tells that Euler had written the book as a blind man and dictated the text to a poor taylor. However, Euler only got completely blind in the year 1771, after an eye surgery. 100'000 copies of the books were sold. It is one of the most successful mathematics textbooks of all times.

- http://serge.mehl.free.fr/chrono/Euler.html
- wp/Contributions_of_Leonhard_Euler_to_mathematics
- https://www.storyofmathematics.com/18th_euler.html