Guillaume François Antoine de l'Hôpital

Guillaume de l'Hôpital was a French nobleman with a passion for mathematics. Suffering from severe myopia, he abandoned his military career and devoted himself to study, becoming the author of the first differential calculus textbook in history in 1696.

However, behind what he "did" there is a rather peculiar story that mixes money, contracts and copyrights:

He bought discoveries: L'Hôpital wasn't a brilliant enough mathematician to discover great theorems on his own, but he had plenty of money. Therefore, he paid an annual salary of 300 francs to the Swiss mathematical genius Johann Bernoulli.

The confidentiality agreement: In exchange for that money, Bernoulli was obliged to send him his new mathematical discoveries in secret and let the marquis use them as he wished.

The legal "theft": Using the material Bernoulli sent him, l'Hôpital compiled and published his famous book. It included a revolutionary method for solving difficult mathematical limits, which is now studied at universities worldwide as l'Hôpital's Rule.

Guillaume François Antoine de l'Hôpital lived for 43 years.

🍼 Born: 1661

⚰️ Died: 1704

🎂 Age at death: 43 years

Yes 😭. L'Hôpital and Marie-Charlotte de Romilley had children, although biographical sources do not always agree on the details.

It is known that they had a son, Jean-Baptiste de l'Hôpital, who inherited the title of marquis after Guillaume's death in 1704.

From Guillaume François Antoine de l'Hôpital (1661–1704):

Wife: Marie-Charlotte de Romilley de La Chesnelaye. They married in 1698.

Friends and colleagues: he had relationships with important mathematicians of his time, especially Johann Bernoulli, with whom he corresponded about calculus and mathematics.

He was also intellectually connected with Jean Bernoulli and other members of the French and European scientific community.

Fun fact: Her relationship with Johann Bernoulli was quite controversial after her death, because a dispute arose over how much of the content of her famous book came from Bernoulli's work.

Guillaume François Antoine de l'Hôpital (1661–1704) was a French mathematician, famous above all for L'Hôpital's rule, used to calculate certain limits in calculus.

Born: 1661, Paris, France 🇫🇷

Died: February 2, 1704, Paris

Nationality: French

Profession: mathematician and aristocrat

Personality: He was very interested in mathematics and science, and corresponded with other great mathematicians of his time.

Important work: Analyse des infiniment petits pour l'intelligence des lignes courbes (1696), one of the first books on differential calculus.

Fun fact: the rule that bears his name is related to limits of shapes such as 0/0 and ∞/∞.

And yes: “de l'Hôpital” was an aristocratic title/surname; it doesn't mean he was a doctor or worked in a hospital. 😭

She mainly lived in France, especially in Paris. 🇫🇷

He also spent time at his family properties, such as the castle of Sainte-Mesme, near Paris, which belonged to his family.