Editing Leonhard Euler (section)

==Personal life==
On 7 January 1734, Euler married Katharina Gsell, daughter of [[Georg Gsell]], a painter at the Academy Gymnasium in Saint Petersburg.{{sfn|Gekker|Euler|2007|p=[https://books.google.com/books?id=Ta9bz1wv79AC&pg=PA402 402]}} The couple bought a house by the [[Neva River]].

Of their 13 children, five survived childhood,<ref name="novaacta" /> three sons and two daughters.{{sfn|Calinger|1996|p=129}} Their first son was [[Johann Euler|Johann Albrecht Euler]], whose godfather was [[Christian Goldbach]].{{sfn|Calinger|1996|p=129}}

Three years after his wife's death in 1773,<ref name="thiele" /> Euler married her half-sister, Salome Abigail Gsell.{{sfn|Gekker|Euler|2007|p=[https://books.google.com/books?id=Ta9bz1wv79AC&pg=PA405 405]}} This marriage lasted until his death in 1783.

His brother Johann Heinrich settled in St. Petersburg in 1735 and was employed as a painter at the academy.{{sfn|Calinger|1996|pp=157–158}}

Early in his life, Euler memorized [[Virgil]]'s ''[[Aeneid]]'', and by old age, he could recite the poem and give the first and last sentence on each page of the edition from which he had learnt it.<ref>{{Cite web |last=Meade |first=Phil |date=1999-11-27 |title=Letter: Uncommon talent |url=https://www.newscientist.com/letter/mg16422147-400-uncommon-talent/ |access-date=2024-09-22 |website=www.newscientist.com |language=en-US}}</ref><ref>{{Cite book |last=Nahin |first=Paul J. |author-link=Paul J. Nahin |url=https://books.google.com/books?id=m3GYDwAAQBAJ&dq=aeneid+euler&pg=PA326 |title=Dr. Euler's Fabulous Formula: Cures Many Mathematical Ills |publisher=Princeton University Press |year=2017 |isbn=978-0-691-17591-1 |series=Princeton Science Library |location=Princeton Oxford |pages=326 |language=en}}</ref> Euler knew the first hundred prime numbers and could give each of their powers up to the sixth degree.<ref name=":2" /> 

Euler was known as a generous and kind person, not neurotic as seen in some geniuses, keeping his good-natured disposition even after becoming entirely blind.<ref name=":2">{{Cite news |last=Lynch |first=Peter |date=2021-01-21 |title=Euler: a mathematician without equal and an overall nice guy |url=https://www.irishtimes.com/news/science/euler-a-mathematician-without-equal-and-an-overall-nice-guy-1.4455424 |access-date=2024-12-09 |work=The Irish Times}}</ref>

===Eyesight deterioration===
Euler's eyesight worsened throughout his mathematical career. In 1738, three years after nearly dying of fever,{{sfn|Gautschi|2008|p=6}} he became almost blind in his right eye. Euler blamed the [[cartography]] he performed for the St. Petersburg Academy for his condition,<ref name="blindness" /> but the cause of his blindness remains the subject of speculation.<ref name="righteye" /><ref name="bullock"/> Euler's vision in that eye worsened throughout his stay in Germany, to the extent that Frederick called him "[[Cyclopes|Cyclops]]". Euler said of his loss of vision, "Now I will have fewer distractions."<ref name="blindness" /> In 1766 a [[cataract]] in his left eye was discovered. Though [[Couching (ophthalmology)|couching of the cataract]] temporarily improved his vision, complications rendered him almost totally blind in the left eye as well.<ref name="volumes"/> His condition appeared to have little effect on his productivity. With the aid of his scribes, Euler's productivity in many areas of study increased;{{sfn|Gautschi|2008|pp=9–10}} in 1775, he produced, on average, one mathematical paper per week.<ref name="volumes" />

=== Death ===
[[File:Euler Grave at Alexander Nevsky Monastry.jpg|thumb|Euler's grave at the [[Alexander Nevsky Lavra|Alexander Nevsky Monastery]]]]

In St. Petersburg on 18 September 1783, after a lunch with his family, Euler was discussing the newly discovered planet [[Uranus]] and its orbit with [[Anders Johan Lexell]] when he collapsed and died of a [[brain hemorrhage]].<ref name="righteye" /> {{ill|Jacob von Staehlin|de}} wrote a short obituary for the [[Russian Academy of Sciences]] and Russian mathematician [[Nicolas Fuss]], one of Euler's disciples, wrote a more detailed eulogy,<ref name="novaacta" /> which he delivered at a memorial meeting. In his eulogy for the [[French Academy of Sciences|French Academy]], French mathematician and philosopher [[Marquis de Condorcet]] wrote:

{{blockquote|''il cessa de calculer et de vivre''— ... he ceased to calculate and to live.<ref name=condorcet/>}}

Euler was buried next to Katharina at the [[Smolensk Lutheran Cemetery]] on [[Vasilievsky Island]]. In 1837, the [[Russian Academy of Sciences]] installed a new monument, replacing his overgrown grave plaque. In 1957, to commemorate the 250th anniversary of his birth, his tomb was moved to the [[Lazarevskoe Cemetery]] at the [[Alexander Nevsky Monastery]].{{sfn|Calinger|2016|pp=530–536}}