50 Fun Facts About Gottfried Wilhelm Leibniz

What kind of snack has the Hanover firm Bahlsen sold under Leibniz's name since 1891?

A butter biscuit took his name only because Leibniz was one of Hanover's most famous residents. Naming foods after famous figures was in fashion, as with Mozartkugeln.

Leibniz's geology book Protogaea includes his drawing of the reconstructed skeleton of which mythical creature?

The unicorn he drew was a fanciful rebuild from fossil bones found in the Harz region. Such bones were then ground up and sold as medicine.

Which English scientist secretly wrote the 1713 committee report that ruled against Leibniz in the calculus dispute?

Isaac Newton presided over the very body whose committee judged the quarrel, and he drafted its verdict himself. Historians now accept that both men reached calculus independently.

What did Leibniz do at age 50, only to change his mind when the answer took too long?

Proposed marriage to a woman whose name is lost, then withdrew the offer while she was still deciding. Leibniz stayed single for the rest of his life.

Which number system, which Leibniz saw as a symbol of God's creation, did he set out in a 1703 paper?

Binary needs only the digits 0 and 1, which Leibniz read as an image of creation out of the void. Every modern computer now runs on it.

Leibniz's first paid post, in Nuremberg, was keeping the records of a club devoted to which pursuit?

Alchemy was a subject he knew fairly little about, yet he presented himself as deeply learned and was taken on with a salary.

Voltaire mocked Leibniz's claim that this is the best of all possible worlds in which 1759 satire?

Candide drags its naive hero through shipwreck, earthquake and flogging while his tutor insists things could not be better. The caricature shaped how Leibniz was read for generations.

Leibniz often added which noble particle to his surname, though no record shows he was ever ennobled?

Gottfried von Leibniz was how he often introduced himself, yet no document from any government of his day has been found granting him nobility.

Who was the only member of the Hanover court to attend Leibniz's funeral in 1716?

His secretary alone came, because Leibniz had fallen so far from favour that even the king, who was near Hanover, stayed away. The grave lay unmarked for over 50 years.

Leibniz went to Paris in 1672 hoping to persuade Louis XIV to invade which land and spare Germany?

Egypt was his bait to turn French armies away from German soil. The plan went nowhere, though Napoleon's 1798 invasion looks like a late, unwitting version of it.

In which Saxon city, where his father taught moral philosophy, was Leibniz born in 1646?

Leipzig was also where he entered university at 14, and where the faculty later refused him a doctorate, most likely for being too young.

Leibniz took his doctorate at the University of Altdorf in which subject, then turned down a professorship there?

Law was the doctorate his home university had refused him, so he moved to Altdorf and submitted a thesis on puzzling court cases within months.

Which calculus symbol did Leibniz introduce in 1675 as a stretched letter S, short for summa?

The integral sign first appears in his private notes from late 1675, and it is still written the way he drew it.

What was the name of Leibniz's machine, the first able to add, subtract, multiply and divide?

Stepped reckoner was its name, and its fine gearwork outran the craftsmen of the day. One machine lay forgotten in a Göttingen attic until workmen found it in 1876.

Besides advising on politics, which post did Leibniz hold for the dukes of Brunswick in Hanover and Wolfenbüttel?

Librarian was the post that mattered most: the catalogue he devised at Wolfenbüttel became a model for many of Europe's largest book collections.

What name did Leibniz give to the simple, partless substances that he said make up the whole universe?

Monads never act on one another, he argued, yet each is like a little mirror of the entire universe, following its own built-in script.

Leibniz was barred from joining the Hanoverian court in London until he finished which long-overdue project?

A family history of his employers, the Brunswicks, had been commissioned nearly 30 years before. He combed archives in Germany, Austria and Italy for it and never finished.

Which ancient Chinese book of hexagrams did Leibniz say matched his arithmetic of ones and zeros?

I Ching hexagrams, sent to him by the missionary Joachim Bouvet, run from 000000 to 111111 once broken and solid lines are read as digits.

Which Russian ruler, who had taken Leibniz on as an adviser, met him again in 1716?

Peter the Great broke his journey at the spa town of Bad Pyrmont to see him. Leibniz had been following Russian affairs since 1708.

The series 1 − 1/3 + 1/5 − 1/7 …, named for Leibniz, adds up to a quarter of which constant?

Pi drops out of this simple pattern of odd fractions, though very slowly. The Indian mathematician Madhava had found the same series centuries before Leibniz did.

Which physicist became Leibniz's mentor in Paris in 1672 and set him on a course of mathematical self-study?

Christiaan Huygens showed the newcomer how much mathematics he lacked and handed him a reading list. Within about three years the pupil had devised his own calculus.

Which London body elected Leibniz a fellow in 1673 after he demonstrated his arithmetic machine there?

The Royal Society saw only a wooden model that February, yet made him a fellow in April. Decades later the same body would rule against him over calculus.

Which philosopher, author of the then-unpublished Ethics, did Leibniz visit in The Hague in 1676?

Baruch Spinoza spent several days in intense discussion with his visitor and died very soon afterwards. Leibniz admired his intellect but was dismayed by his conclusions.

Which British king, previously Leibniz's employer as Elector of Hanover, left him behind in Germany in 1714?

George I had little warmth for his court philosopher, and taking him to London would have insulted the English rival seen as the winner of the calculus dispute.

Which friend and patron of Leibniz died weeks before she would have inherited the British throne?

Electress Sophia collapsed in the gardens of Herrenhausen in June 1714, less than two months before Queen Anne died. Her son took the crown instead.

Leibniz hoped a symbolic language of thought would let people in a dispute sit down together and do what?

Calculate was his answer: with ideas written as exact symbols, an error would show at a glance, like a slip in a sum. The dream anticipated symbolic logic.

Which word did Leibniz coin for the title of his 1710 book defending God's goodness in a world containing evil?

Theodicy joins the Greek for God and justice, and the word now names the whole problem of squaring a good God with suffering.

To argue that machinery cannot explain perception, Leibniz imagined walking inside a thinking machine as large as what?

A mill is the image he chose: step inside and you would find only parts pushing one another, never a perception. Philosophers still call the puzzle Leibniz's gap.

Leibniz's pre-established harmony is often pictured as mind and body agreeing like two matched what?

Clocks set going together keep the same time without touching, and Leibniz held that mind and body agree in just that way, synchronised in advance by God.

Leibniz set out to extend the adding machine of which earlier mathematician so that it could also multiply?

Blaise Pascal had built a device that could only add and subtract. Leibniz learned of it from reading the Pensées and set about making gears multiply and divide too.

Which way of writing a derivative, still taught in every calculus class, did Leibniz devise in the 1670s?

dy/dx treats a slope as a ratio of two tiny differences. Leibniz put all his mathematical discoveries down to good notation, and this one became the standard in calculus textbooks.

Which mathematical term did Leibniz introduce for quantities such as a curve's tangent or ordinate?

Function began as his word for geometric quantities that depend on a curve. Only in the following century did it shed the geometry and take on its modern meaning.

Which principle of Leibniz holds that no fact or event exists without an explanation of why it is so?

Sufficient reason pushed him to ask why anything exists at all. His answer was a necessary being that carries the ground of its own existence within itself.

To show that no two things are ever exactly alike, Leibniz liked to point to which garden objects?

Leaves may look identical, but he argued that two things alike in every respect would simply be one thing, so some difference must always be there to find.

Leibniz shelved his book-length reply to which English philosopher's Essay after that author died in 1704?

John Locke could no longer answer back, so Leibniz lost the desire to publish. The New Essays finally appeared in 1765 and began the recovery of his reputation.

Leibniz's vis viva, or 'living force', was an early version of which quantity in modern physics?

Kinetic energy is exactly half of his vis viva, mass times velocity squared. Rivals championed momentum instead, and it turned out that both are conserved.

Leibniz spent years trying to pump water out of the Harz silver mines using which power source?

Wind was meant to drive his pumps, but the scheme did little for the flooded mines and the duke shut it down in 1685.

Which admiring label have later writers often attached to Leibniz?

The last universal genius fits because such range became a rarity after his lifetime, once the Industrial Revolution turned scholars into specialists.

Leibniz was born in 1646, shortly before the end of which conflict that had ravaged central Europe?

The Thirty Years' War left German lands exhausted and fragmented, which is why the young Leibniz later schemed to keep the armies of Louis XIV pointed elsewhere.

In which city did Leibniz found an academy of sciences in 1700 and serve as its first president?

Berlin was the only one of his academy campaigns to bear fruit: he also pressed for learned academies in Dresden and Vienna, without success.

Which ever-hopeful tutor in Voltaire's 1759 satire is a caricature of Leibniz and his optimism?

Pangloss keeps insisting that everything is for the best, whatever disaster strikes, and the parody was so vivid that many readers took it for an accurate picture of Leibniz.

Leibniz spent his final year debating space and time by letter with which English clergyman?

Samuel Clarke defended absolute space against Leibniz's view that space is only relations between things. The exchange began with a letter to the Princess of Wales and ended with Leibniz's death.

In which journal, which he had helped launch two years before, did Leibniz first publish his calculus in 1684?

Acta Eruditorum printed the paper without proofs, and Jacob Bernoulli called it an enigma rather than an explanation.

Leibniz laid the foundations for which quantity computed from a square array of numbers, found independently in Japan?

The determinant was also discovered by Seki Takakazu in Japan, with neither man aware of the other. Leibniz used it to solve linear equations decades before Cramer published his rule.

Which follower of Leibniz ranks among the most eminent German philosophers between Leibniz and Kant?

Christian Wolff met Leibniz only three times but built a modified version of his system, and that dogmatic retelling is blamed for harming the master's reputation.

The Leibniz wheel, a drum with teeth of graded length, later drove which first mass-produced mechanical calculator?

The arithmometer put his toothed drum into offices generations after his death. Leibniz's own machines never managed to carry digits reliably.

Which thinker called Leibniz's puzzle of why anything exists at all the fundamental question of metaphysics?

Martin Heidegger gave it that rank two centuries later. Leibniz had framed it as a choice between something and nothing, and answered with a necessary being.

Leibniz once wrote under the name of a fictitious nobleman to sway the election of which country's king?

Poland chose its kings by vote, and Leibniz, posing as a local noble, argued for the German candidate. His man lost.

The mathematician Norbert Wiener suggested that Leibniz be named patron saint of which young field?

Cybernetics was Wiener's own creation, and he saw the computing machine as simply Leibniz's dream of mechanised thought made real.

A huge impact crater named Leibnitz, an old spelling of his surname, lies on which body?

The Moon carries the crater on its far side, so it can never be seen from Earth. It matches the size of Clavius, one of the giants of the near side.