"I don't read, I write", said this scientist considered to be one of the greatest, if not the greatest mathematician of the 20th century, who revolutionized geometry like Einstein did physics.

Disappeared in 2014 at the age of 86, the math giant, who ended up as a hermit, spent his life putting his thoughts down on paper.

Tens of thousands of pages, mathematical and literary notes, as abundant as its history is singular.

Born in 1928 in Berlin to a Russian Jewish father and a German mother, the child was entrusted to a Protestant family in France when his parents, militant anarchists, joined the Spanish Civil War.

In 1940, the young stateless person (he remained so until 1971) was interned with his mother in a camp in Lozère.

His father dies in Auschwitz.

He passed his baccalaureate at the Cévennes high school in Chambon-sur-Lignon, where he was noticed.

Highly recommended, the student went to take the best courses in Paris and then Nancy, where a professor presented him with 14 problems that had still not been solved.

Six months later, to everyone's amazement, Grothendieck solved them all - the equivalent of six theses.

He spent twelve years teaching at the Institut des Hautes Etudes Scientifiques (IHES), where his algebraic geometry seminars became legendary, and was crowned in 1966 by the Fields medal, the "Nobel" of maths.

environmental activist

But in the 1970s, he left the high sphere of mathematics, abandoned research.

Pacifist, ecologist, he does not support the idea that basic sciences can be used to manufacture weapons and destroy the planet.

He founded "Survive et vivre", a radical ecology movement.

His militancy earned him the abolition of his chair at the College de France.

Photo released by IHES on November 18, 2014 of Alexandre Grothendieck giving a course at IHES in the 1960s HO - IHES/AFP/Archives

"Récoltes et semailles" was created between 1983 and 1986, when he was teaching at the University of Montpellier.

A “monster”, he said, of 1,500 pages, a “braid” interweaving reflections on maths and their poetry, ecology, spiritual meditations … and harsh criticism against his students who would have betrayed his ideal.

The text is like a "promenade" in the intimacy of his thought.

Without filter, in a clear style that the genius also wants to address to laymen.

He sends 150 copies to his acquaintances.

The prints circulate in the middle, then versions are put online.

Grothendieck writes a final one, which he wants to reveal to the general public this time

He entrusts the mission to the scientific journalist and philosopher of science Stéphane Deligeorges.

"We had an appointment at Place Saint-Sulpice in Paris, it was cold. Shourik - his nickname - arrived in sandals, barefoot, his typescript under his arm. He made me promise to publish it", says t he told AFP.

"Flayed"

“It was unparalleled, even among mathematicians. Shourik wrote what he had in mind without calculating his audience. He was inhabited, had a different cortex, an insane power of work. respected immensely", he is moved.

His own publisher, Christian Bourgois, took an interest in it, then gave up.

The project still fails in another.

Too big, and probably also defamatory given the "violence of the attacks" against his students, some of whom received the Fields medal, remembers Jean-Pierre Bourguignon, who headed IHES.

Photo released by IHES on November 18, 2014 of Alexandre Grothendieck (g) and French mathematician Laurent Schwartz in Bures-sur-Yvettes in the 1960s - IHES/AFP/Archives

Stéphane Deligeorges hangs on.

Despaired a little when in 2010, Grothendieck, then recluse in Ariège, changed his mind and opposed any publication during his lifetime.

The ban was lifted after his death in 2014, and the journalist finally convinced Gallimard by arguing the importance of this "heritage".

Considered sufficiently literary, he asked for a colossal editing job, "the most complex of my 18-year career", testifies the editor, Sophie Kucoyanis.

Released in January and printed in 5,000 copies, the book is off to a good start.

"There was a real expectation from booksellers," she enthuses.

Translation requests are coming.

"Wonder of Creation"

Admittedly "80% of the text" is for the strong in math, but "20% is readable by all", according to this non-scientist.

Who was "touched" by the passages on the "wonder of creation" that the author compares to childhood.

"Grothendieck thought of the math that is written, showing that it is not formulas but the creation of concepts, and that the higher we go in abstraction, the more we manage to overcome the difficulties", adds Jean-Pierre Bourguignon.

The story does not end there.

When he died, more than 70,000 handwritten pages were recovered from his house in Ariège, where he had walled himself in silence.

His five children have dropped them off at a Parisian bookseller, who hopes to sell them at exorbitant prices.

In fly-like writing, there is this moving notebook retracing the convoys of deported Jews.

The rest?

Notes "on everything", often "delusional", testifies the bookseller, Jean-Bernard Gillot.

The archiving work promises to be immense and could, perhaps, unearth a treasure.

© 2022 AFP