David Hilbert (January 23, 1862 – February 14, 1943) was a German mathematician, recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. He discovered and developed a broad range of fundamental ideas in many areas, including invariant theory and the axiomatization of geometry. He also formulated the theory of Hilbert spaces, one of the foundations of functional analysis. He is also known as one of the founders of proof theory, mathematical logic and the distinction between mathematics and metamathematics.

Hilbert, the first of two children and only son of Otto and Maria Therese (Erdtmann) Hilbert, was born in either Königsberg (according to Hilbert's own statement) or in Wehlau (today Znamensk, Kaliningrad Oblast)) near Königsberg. In the fall of 1872, he entered the Friedrichskolleg Gymnasium. In 1879 he transferred and, later, graduated from (spring 1880) the more science-oriented Wilhelm Gymnasium. Upon graduation he enrolled (autumn 1880) at the University of Königsberg, the "Albertina". In the spring of 1882, Hermann Minkowski returned to Königsberg from Berlin and entered the university. In 1884, Adolf Hurwitz arrived to Göttingen as an Extraordinarius, i.e., an associate professor. Hilbert obtained his doctorate in 1885, with a dissertation, written under Ferdinand von Lindemann, titled Über invariante Eigenschaften spezieller binärer Formen, insbesondere der Kugelfunktionen ("On the invariant properties of special binary forms, in particular the spherical harmonic functions").

Hilbert remained at the University of Königsberg as a professor from 1886 to 1895. In 1892, Hilbert married Käthe Jerosch (1864–1945), "the daughter of a Konigsberg merchant, an outspoken young lady with an independence of mind that matched his own". While at Königsberg they had their one child Franz Hilbert (1893–1969). In 1895, as a result of intervention on his behalf by Felix Klein he obtained the position of Chairman of Mathematics at the University of Göttingen, at that time the best research center for mathematics in the world and where he remained for the rest of his life.

Among the students of Hilbert were: Hermann Weyl, the champion of chess Emanuel Lasker, Ernst Zermelo, and Carl Gustav Hempel. John von Neumann was his assistant. At the University of Göttingen, Hilbert was surrounded by a social circle of some of the most important mathematicians of the 20th century, such as Emmy Noether and Alonzo Church. Among his 69 Ph.D. students in Göttingen were many who later became famous mathematicians, including (with date of thesis): Otto Blumenthal (1898), Felix Bernstein (1901), Hermann Weyl (1908), Richard Courant (1910), Erich Hecke (1910), Hugo Steinhaus (1911), Wilhelm Ackermann (1925). Between 1902 and 1939 Hilbert was editor of theMathematische Annalen, the leading mathematical journal of the time.

Good—he did not have enough imagination to become a mathematician.

—Hilbert's response upon hearing that one of his students had dropped out to study poetry.

Hilbert lived to see the Nazis purge many of the prominent faculty members at University of Göttingen, in 1933. Among those forced out were Hermann Weyl, who had taken Hilbert's chair when he retired in 1930, Emmy Noether and Edmund Landau. One of those who had to leave Germany was Paul Bernays, Hilbert's collaborator in mathematical logic, and co-author with him of the important book Grundlagen der Mathematik (which eventually appeared in two volumes, in 1934 and 1939). This was a sequel to the Hilbert-Ackermann book Principles of Mathematical Logic from 1928.

About a year later, he attended a banquet, and was seated next to the new Minister of Education, Bernhard Rust. Rust asked, "How is mathematics in Göttingen now that it has been freed of the Jewish influence?" Hilbert replied, "Mathematics in Göttingen? There is really none any more."

By the time Hilbert died in 1943, the Nazis had nearly completely restructured the university, many of the former faculty being either Jewish or married to Jews. Hilbert's funeral was attended by fewer than a dozen people, only two of whom were fellow academics, among them Arnold Sommerfeld, a theoretical physicist and also a native of Königsberg. News of his death only became known to the wider world six months after he had died.

On his tombstone, at Göttingen, one can read his epitaph, the famous lines he had spoken at the end of his retirement address to the Society of German Scientists and Physicians in the fall of 1930:

Wir müssen wissen.

Wir werden wissen.

As translated into English the inscriptions read:

We must know.

We will know.

The day before Hilbert pronounced this phrase at the 1930 annual meeting of the Society of German Scientists and Physicians, Kurt Gödel—in a roundtable discussion during the Conference on Epistemology held jointly with the Society meetings—tentatively announced the first expression of his incompleteness theorem, the news of which would make Hilbert "somewhat angry".

Montferrand was born in paroisse of Chaillot, France (now, 16th arrondissement of Paris). He was styled at birth Henri Louis Auguste Leger Ricard dit de Montferrand. His father, Benois Ricard, was a career horse trainer, that died when Auguste was a child. Grandfather, Leger Ricard, was a bridge engineer. Mother, née Marie Francoise Louise Fistioni, remarried Antoine de Commarieux, who is credited with educating Auguste.

In 1806, Montferrand joined the former Académie d'architecture, class of Charles Percier and Pierre Fontaine. Soon, he was summoned to Napoleon's Army, and served a brief tour of duty in Italy. Montferrand married Julia Mornais in 1812. The next year, he was again drafted into the Army when the allied troops were closing in on Dresden. Montferrand served with distinction in Thuringia engagements, and was awarded Légion d'honneur for valor in the Battle of Hanau.

When hostilities ended, new construction in defeated France was out of the question. Montferrand worked on a few unimportant jobs, spending three years in basic draftsmanship and seeking opportunities overseas. In 1815, he was awarded an audience to Alexander I of Russia and presented the Tsar with an album of his works. Post-war Russia presented a wealth of opportunities.

In summer 1816, Montferrand landed in Saint Petersburg, carrying a recommendation letter from Abraham Louis Breguet. He rented a room near the house of Fyodor Wigel, the secretary of Construction Commission, and applied to Agustín de Betancourt, the chairman of this commission (and a partner of Breguet in 1790s). Betancourt, impressed by Breguet's letter and Montferrand's drawings, offered him the desk of Head of Draftsmen, but Montferrand preferred a lower rank of senior drafrsman. December 21, 1816 he officially joined the Russian service.
      

Monferrand divorced with his first wife soon after settling in St.Petersburg. Divorce and extravagant lifestyle caused him a lot of debts; in 1831 he refinanced it with a loan from the Tsar's Cabinet. In 1834 he was awarded a lifelong pension and a 100,000 lump sum, enabling him to settle all accounts and build his own house. As his finances improved, Montferrand became a compulsive collector of arts and amassed 110 Greek and Roman statues and hundreds of lesser items. Witnesses reported that "any Sunday he indulged in rearranging the statues, using 25 laborers from 9 a.m. to lunch time". When Monferrand died, the Hermitage Museum failed to buy out the collection, and it dispersed.

In 1835, Montferrand married Elise Debonniere, an actress who arrived in Saint Petersburg nine years earlier. The relationship began in 1820s and lasted until his death. The Montferrands adopted Henri, Elise's nephew.

Auguste de Montferrand died in Saint Petersburg in 1858, the year St. Isaac's Cathedral was completed. His will to be buried in the vault of that cathedral could not be executed, because he was not of Orthodox faith. His body was returned to France and was buried in the Cimetière de Montmartre, Paris, France, next to his mother. The grave, once believed to be lost, was identified in 1986 in Chemin des Gardes row. It bears the name Louise Fistioni and AM, Montferrand's initials.

Ulrika Eleonora (23 January 1688 – 24 November 1741), also known as Ulrika Eleonora the Younger, was Queen regnant of Sweden from 30 November 1718 to 29 February 1720, and then Queen consort until her death.

She was the youngest child of King Charles XI and Queen Ulrika Eleonora the Elder and named after her mother. After the death of her brother King Charles XII in 1718, she claimed the throne over the rights of her nephew Charles Frederick, Duke of Holstein-Gottorp, the only son of her late elder sister, on basis of being the closest surviving relative of the deceased king (the idea of proximity of blood) and the precedent of Queen Christina, though not his heiress in primogeniture. The succession discussions ultimately ended in her favour after she had agreed to abolish the absolute monarchy. She abdicated the Swedish throne in 1720 and was succeeded by her consort, Landgrave Frederick I of Hesse-Kassel.

A princess and spinster, she took care of her dominating grandmother, Hedwig Eleonora of Holstein-Gottorp, during her brother's absence in the Great Nordic War. During this period, her older sister, Princess Hedvig Sophia of Sweden, Duchess of Holstein-Gottorp, was the heir to the throne. Her situation began to change after the death of her older sister in 1708. As her brother refused to marry, and as she was the only royal representative in Sweden, she was in 1713 named as regent during the king's absence by the government and by her grandmother, and thus became the puppet to many powers struggling for influence in a country without a real heir. The choice now stood between Princess Ulrika Eleonora and her nephew, her older sister's son, the duke of Holstein-Gottorp. Her accession as regent and president of the parliament was treated with great enthusiasm. The parliament was in opposition to her brother as they wanted to abolish the absolute monarchy and reinstate the power of the parliament.

After her grandmother's death in 1715 she became the center of the court, and this was most likely one of the most happy periods of her life. It was during this period, in the year of 1715, that she married Landgrave Frederick I of Hesse-Kassel, but the marriage, which on her side was a marriage of love, was to be but another one of the many attempts to use her as a political puppet. Her husband had married her with the intent to reach the throne through her, and immediately started to work to get her appointed as heir to the throne before her nephew, and the "Hesse-party" and the "Gottorp-party" stood against each other in the struggle to the throne. When her brother the king was killed in 1718, the "Hesse-party", as they were called, secured Ulrika Eleonora's succession to the throne before her nephew, the duke of Holstein-Gottorp. They managed to secure the support of the opposition, who wanted to abolish the absolute monarchy from 1680 and reinstate the rule of the parliament. Her reign took place in the middle of the last years of the Great Nordic War.

In her accession, she had to give her consent to a new constitution, which greatly limited the power of the monarch, to accomplish this. Thereafter, she was formally elected monarch and crowned in Uppsala in March 1719. She was strongly in favor of an absolute monarchy, and had agreed to the new constitution only to secure the throne from her nephew. She supported her husband's political ambitions and wanted him to become co-regent, following the example of King William III of England and Queen Mary II of England, but this was not permitted by the parliament, as co-reigning had been forbidden in Sweden since the 15th century, and she therefore abdicated in his favour after just one year of her reign, which succession was confirmed by the Riksdag of the Estates. She often talked about her abdication as the great sacrifice of her life. Frederick thereafter succeeded her on the Swedish throne as King Frederick I in 1720.

Ulrika Eleonora had married for love and was known to be fiercely loyal to Frederick. His extramarital affairs increased after he lost his real power as a king. At least until 1724, the Queen expressed the hope that she would give birth to an heir. In 1730, her spouse became the first king in Swedish history to have an official mistress, the young noble Hedvig Taube, who was given the title countess of Hessenstein. The Queen's reaction to this has never been known and she never commented on it but did retire to religion and charity, although she was made official regent of Sweden during the absence of her spouse on two occasions: in 1731 and in 1738. 

Queen Ulrika Eleonora died of smallpox in 1741 after a childless marriage. The succession thereafter was marked by recurring plotting. The reigns of Ulrika Eleonora and her husband saw the birth of the era of Swedish history traditionally known as the Age of Liberty, when the monarch had to give up most of his power to the aristocracy.