In high summer 1751, at a long table at Sanssouci, two men sit opposite each other: a sharp-tongued fifty-six-year-old Frenchman and a Prussian king, thirty-nine, flautist and enlightener. They speak French, read each other verses, laugh about the clergy. For three years Voltaire is a guest at the court of Frederick II. Then they fall out. But the tone of this table — not a doctrine, not a book, but a particular way of dealing with the supernatural — diffuses from there into Prussian elite education, later into Humboldt's university reform, then into Horace Mann's American school reform, and finally, via Meiji Japan, into the whole world. When today an educated person hears about a near-death experience and reflexively rolls their eyes, they are not hearing themselves. They are hearing this table.
Who was Voltaire actually?
François-Marie Arouet, born 1694 in Paris, died 1778 in the same city. Educated by Jesuits, later their most radical opponent. His long life (eighty-four years) coincides almost exactly with the lifetime of Emanuel Swedenborg (1688–1772), his intellectual antipode — the two never met in person, and there is no documented correspondence between them either.
Voltaire was no atheist. He was a deist: an abstract God of reason sets the world in motion, then withdraws, does not meddle in details, hears no prayers. "Si Dieu n'existait pas, il faudrait l'inventer." — but please a God without mysticism, without miracles, without personal encounter. His favourite enemy-word for everything that went beyond that was "enthousiasme" — in the French of his day not "enthusiasm" but "fanaticism", "religious rapture", "mystical delusion". The article Enthousiasme in Voltaire's Dictionnaire philosophique (1764) lists everything he considers laughable: visions, raptures, encounters with spirits, prophetic dreams. Method: not refutation but mockery.
It is important to recognise what was good in Voltaire: he fought with all his rhetorical weight against torture, against the judicial arbitrariness of absolutist criminal procedure, for religious freedom. In the Calas affair (1762) and the Sirven affair (1764) he forced posthumous rehabilitations for Protestant families whom Catholic France had judicially destroyed. That is not small. Modern human rights still live from this inheritance.
His price: he taught educated Europe that the mystical was not worthy of serious response. Not false, not refuted — but below the laughter threshold. That is a different thing from an argument. It is a stance.
Sanssouci 1750–1753
The correspondence between Voltaire and Frederick — at the time a twenty-eight-year-old crown prince — begins in August 1736. Frederick writes to Cirey, where Voltaire lives with Émilie du Châtelet; Voltaire replies. Over four decades, more than six hundred letters will pass between them — one of the most important correspondences of the 18th century, fully edited in the critical Berlin Academy edition and freely available via Project Gutenberg. They write about verses, politics, war, philosophy, but above all: about the style in which an educated person thinks, writes, presents himself.
On 10 July 1750 Voltaire finally moves to Potsdam — with the title of a Prussian chamberlain, with a pension, an order, and an apartment at Sanssouci. The famous round-table meals at the palace are less lectures than highly polished conversations: Frederick, Voltaire, the mathematician Maupertuis, the Marquis d'Argens, the materialist physician La Mettrie (author of L'homme machine). French is the official language, Latin the old one, German the language of coachmen and the guard. This is not just courtly taste — it is a positioning.
In 1753 the friendship breaks down over the Maupertuis dispute (Voltaire publicly mocks the Academy president whom Frederick is defending). Voltaire flees, is detained in Frankfurt on Frederick's orders, eventually released. They never see each other again. But the correspondence resumes after a few years, continues until Voltaire's death in 1778, and remains one of the most intimate love-hate friendships of the century.
What Frederick took on — not scepticism, but elegance
Frederick did not need Voltaire for his religious scepticism. He had that from home: a father whose Calvinist harshness he hated; a life path on which, as an eighteen-year-old in 1730, he tried to flee Prussia, and for which his father forced him to attend the execution of his closest friend Hans Hermann von Katte. Frederick came out of this experience as a man who structurally distrusted the Christian.
What Voltaire gave him was not the scepticism but the elegance with which to handle it. A royal habitus in which the mystical is not loudly combatted but kept below the threshold of attention. The method of the fine smile. The method of mocking distance. Frederick, in his letters to his sister Louisa Ulrika, does not call Swedenborg a "fraud" or "heretic" — he calls him an "enthusiast", plays with the usual topoi (superstition, fantasy, bad digestion). Precisely this non-aggressive mockery is Voltaire's real gift to the Prussian court and later academic culture. We have documented this concrete reaction in detail in the family micro-chapter around 1760.
The 1763 school regulation — not Voltairean in wording
Twelve years after Voltaire's arrival at Sanssouci, on 12 August 1763, Frederick II promulgated the General-Land-Schul-Reglement, which introduced compulsory schooling in Prussia for children aged five to thirteen and was to become, over a century and a half, the worldwide model of the modern school.
Anyone reading the text will search in vain for Voltaire. It was drafted by Johann Julius Hecker (1707–1768), Lutheran theologian, pietist, founder of the Berlin Realschule. The stated aim is "reasonable as well as Christian instruction of youth toward true fear of God". Reading, writing, arithmetic, singing, catechism, biblical stories. Supervision by local clergy, inspection by the Protestant consistories. This is pietistic rational piety, not Voltairean mockery of religion.
So Voltaire does not shape the law. He shapes something else that turns out to be more powerful in the long run: the ethos of the educated class from which the inspectors come, in which the teacher seminaries are founded, in which the curricula of the higher schools are written. The village pupil of 1763 prays Bible verses. But the Prussian educational elite — parents, inspectors, university professors — breathes Sanssouci air. Over the next generations this slowly diffuses downward.
This separation between the 1763 law (form) and the later content filtering (spirit) is reconstructed in detail in our article on Prussian schooling.
Humboldt 1810: the academic secularisation
The actual secular step is taken not by Frederick but by Wilhelm von Humboldt, who in 1809 begins as Prussian Section Head for Religion and Education and in 1810 founds the University of Berlin. Humboldt creates the model later copied worldwide as the "German university":
- Academic freedom of research
- Education as an end in itself — not for the church, not for the state, for the subject
- Unity of research and teaching
- Scientific spirit as the leading value across all disciplines
Humboldt is no Voltairean mocker. He is a friendly classicist, a friend of Goethe, a humanist scholar. But the model he institutionalises absorbs the Sanssouci atmosphere as the standard air of the scientific enterprise. Theology remains as a faculty, but withdraws into its confessional own-world. Natural science, philosophy, history define themselves around the methodology of non-mysticism.
Here what was in Voltaire a personal tone becomes an academic constitution. Whoever wants to be a professor in this university must decide: mysticism is private matter or nothing. In the lecture hall, at any rate, not.
1843: Horace Mann brings the system to America
In the summer of 1843, Horace Mann, the school reformer of Massachusetts, took his honeymoon with his second wife Mary Peabody Mann. But he did not travel to Italy or France. He travelled to Prussia to study the schools there. On his return, he wrote the Seventh Annual Report of the Secretary of the Board of Education, which described the Prussian schools as "first of all nations". Over the next decade, with this report, he established the Common School Movement, which created the American public school in the form still recognisable today: class group, lesson clock, teacher seminaries ("normal schools"), canonised choice of material, supervision.
Mann was clever enough to warn against one element: "Prussia's obedience to the authorities". The USA, he said, should adopt the form but not the tone of obedience. In practice this distinction is thin — the form carries the tone with it.
1872: Meiji Japan adopts the Prussian model
In 1868 the Meiji Restoration begins in Japan; in 1871 the Japanese Ministry of Education is established; in 1872 the Gakusei (学制, "school system") is enacted, which introduces compulsory schooling in Japan — on an explicitly Prussian model. Japanese officials travel to Berlin, German advisors to Tokyo. What Japan adopts is not only the Prussian form but also the Prussian-Humboldtian atmosphere: scientific spirit as leading value, tone of non-mysticism, religion as a private matter.
With this the global diffusion is essentially complete. Russia (through Alexander II's reforms), Latin America, later China and the UNESCO standards adopt variants of this model. What we today call "school system" is in its basic structure Prussian — and the atmospheric tone behind it is Voltairean.
Kant: the same zeitgeist, methodically worked through
An important pointer at this point: Kant was part of the same zeitgeist. He grew up in a Voltairean-breathing educated world, he read Voltaire, he took on much of the ethos. If today you open a Kant text in the classroom, you hear the Voltairean ground beneath. Kant absorbed and processed the Sanssouci zeitgeist.
But in his treatment of the supernatural, Kant is methodical where Voltaire is reflexive. Precisely this is the gap between them — and precisely this gap was lost in the 20th century.
- Voltaire hears about Swedenborg, laughs, writes a satirical article.
- Kant hears about Swedenborg, in 1762 sends an English merchant to Stockholm, has the Stockholm fire incident of 19 July 1759 examined in detail, writes in 1763 the Knobloch letter with all the detail confirmations, writes in 1766 the entire book Dreams of a Spirit-Seer, Elucidated by Dreams of Metaphysics, in which he mixes mockery and argument — and fifteen years later, in the Critique of Pure Reason (1781), concludes that theoretical reason can neither prove nor refute such questions.
Today's Kant scholarship (Stengel 2011, Kuehn 2001, Johnson 2002) accordingly reads the Dreams no longer as a wholesale dismissal but as a methodological turning point — see our Kant and Swedenborg article.
What matters for our thread here: Kant represents the Voltairean atmosphere with philosophical discipline. Voltaire mocks; Kant investigates and honestly leaves the question open. In academic practice it was not Kant's method that prevailed but Voltaire's tone. This is one of the intellectual tragedies of the 19th and 20th centuries.
1906: the tone becomes a filter
As long as the Voltairean tone is an elite habitus, it remains flexible. Kepler in the 18th and 19th centuries could still be taught with astrology. Faraday could be appreciated as a Sandemanian Christian. Maxwell could speak about his faith.
With Newton the case is different, and this is important to state clearly: his alchemical and theological manuscripts — several million words, more than half of his written legacy — were locked away immediately after his death in 1727. A commission under Thomas Pellet (Fellow of the Royal Society, appointed by John Conduitt and the other executors to inspect the papers) went through them and stamped most of the alchemical and theological writings as "not fit to be printed". They remained publicly inaccessible for over two hundred years. Only at the Sotheby's auction of the Portsmouth Papers in July 1936 were they scattered and sold; John Maynard Keynes acquired a large portion and, having sifted through them, declared: "Newton was not the first of the age of reason. He was the last of the magicians." Where the Voltairean tone needed institutional filtering to work on Kepler, Faraday and Maxwell, with Newton it had already encountered a private suppression long before. The elite atmosphere was Voltairean — but for most of these scientists the contents at least remained available.
That changes within a surprisingly narrow date window:
- April 1906: death of Pierre Curie, shortly before the planned publication of his Eusapia Palladino findings
- December 1907: death of Lord Kelvin
- 1909: Hugo Münsterberg's public "exposure" of Palladino in New York and Boston — as a distancing ritual of American psychology
- August 1910: death of William James
In four years the bridging figures between top natural science and consciousness research simultaneously lose their voice. The next generation finds no institutional connection any more. This turn is reconstructed in detail in our 1906-pattern article.
What matters here: from this moment on, Voltaire's tone is no longer merely atmosphere but institutional filter. Kepler is an astronomer (astrology struck out). Newton is a mathematician (alchemy struck out). Faraday is an electrical engineer (Sandemanian theology struck out). Maxwell is a field theorist (faith struck out). Textbooks are editorially cleaned. What is not worthy of serious response does not enter the book.
The Prussian-Humboldtian form from 1763/1810 becomes the carrier of this filtering without being its cause. Frederick II — as a pupil of Voltaire, but also as a broadly read eighteenth-century man — would presumably not have shared the mechanistic narrowing of the early 20th century. He was an enlightener, not a positivist.
What we have inherited — and what we may keep
Voltaire has left our world two things, and they can be separated.
The one we may keep: the struggle against torture and judicial arbitrariness, the insistence on religious freedom, the idea that no doctrine justifies the application of force. This inheritance is great and indispensable.
The other we need not keep: the tone that presses the mystical below the laughter threshold before it has even been examined. We have made this tone, via Sanssouci, the Prussian school model, Humboldt's university, Horace Mann's common schools, and Meiji Japan, into the global academic standard. It sits today in the curricula, the appointment committees, the peer reviews, the Wikipedia articles.
Anyone who today reads a carefully documented near-death experience — from Elisabeth Kübler-Ross as pioneer to the peer-review generation around Bruce Greyson, Pim van Lommel, Jeffrey Long and Penny Sartori, supplemented by the German-language line of Wilfried Kuhn (neurology), Walter van Laack (medicine) and Godehard Brüntrup (philosophy), several thousand cases in peer-reviewed journals —, who attends a sitting with a tested medium (Beischel/Windbridge, Schwartz/Veritas, Roy/Robertson Glasgow, the Tressoldi meta-analysis, Lazar/EREAMS, plus Jakob Bösch for the psychiatric inside view), who knows the academic psi research — from J. B. Rhine at Duke University through Walter von Lucadou at the IGPP Freiburg to Puthoff and Targ at SRI, with the Geller experiments in Nature 1974 and the silver futures of Delphi Associates 1982 —, who sets Swedenborg's Stockholm fire incident with Kant's own field confirmation next to themselves, and reflexively rolls their eyes: is not hearing "the science". They are hearing a tone that was refined in 1751 at a table at Sanssouci, was covered there neither by argument nor by investigation, and which through pure institutional diffusion became the world's atmosphere.
This tone we can lay down without touching Voltaire's merits. That is precisely what Kant attempted in 1766. That is precisely the open question of our time.
Sources: Voltaire, Dictionnaire philosophique, Geneva 1764 (articles Enthousiasme, Fanatisme, Superstition). Correspondance de Voltaire avec le roi de Prusse, edited in Théodore Besterman (ed.), Voltaire's Correspondence, Voltaire Foundation Oxford 1968–1977 (over six hundred Voltaire–Frederick letters in total); German edition in the critical Berlin Academy edition; also available via Project Gutenberg. René Pomeau, Voltaire en son temps, 5 vols., Voltaire Foundation 1985–1994 (standard biography). Theodor Schieder, Friedrich der Große. Ein Königtum der Widersprüche, Propyläen 1983. General-Land-Schul-Reglement of 12 August 1763, full text at German History in Documents and Images (GHDI). James Van Horn Melton, Absolutism and the Eighteenth-Century Origins of Compulsory Schooling in Prussia and Austria, Cambridge University Press 1988. Paul R. Sweet, Wilhelm von Humboldt: A Biography, Ohio State University Press 1978–1980 (2 vols., on the 1810 university founding). Horace Mann, Seventh Annual Report of the Secretary of the Board of Education, Boston 1844 (Prussia report on the 1843 trip). Jürgen Herbst, The Once and Future School: Three Hundred and Fifty Years of American Secondary Education, Routledge 1996 (on the Mann reception). Benjamin Duke, The History of Modern Japanese Education: Constructing the National School System, 1872–1890, Rutgers University Press 2009 (on the Gakusei). Immanuel Kant, letter to Charlotte von Knobloch, 10 August 1763, Academy edition vol. 10, pp. 43–48; Dreams of a Spirit-Seer, Königsberg 1766, Academy edition vol. 2, pp. 315–373. Friedemann Stengel, Aufklärung bis zum Himmel: Emanuel Swedenborg im Kontext der Theologie und Philosophie des 18. Jahrhunderts, Mohr Siebeck 2011. Manfred Kuehn, Kant. A Biography, Cambridge University Press 2001.