Dutch autodidact mathematician, philosopher and social activist.
His father Gerrit Mannoury (1825/6, Wormerveer – 11 October 1868) was a sea captain, who died in China, when he was one years old. The message reached his mother Anna van Beek (1834) around 2 December 1868. His brother Jan (4 June 1859, Wornerveer – 29 March 1895, Bussum) became a playwright.
After finishing the higher civil school (HBS , 1885) and the teachers academy “Kweekschool” (with a grant), he started as a teacher, but had to quit because of problems with keeping order in the class (1886). In the following years he studied as a visitor at the University of Amsterdam (UvA) to become a teacher of mathematics, accounting, mechanics (1902) and became a skilled educator, teaching mathematics privately and at schools.
His skills in the field of topology (Lois cyclomatiques, 1897) were noticed by the mathematician Diederik Korteweg, who gave him private lessons and also granted him to give private lessons at the UvA (1903). From 1917 till 1937 he was probably the only professor in mathematics at the UvA that had not a PhD degree. His major student was L. E. J. Brouwer, both became major significs, a Dutch counterpart of the Vienna circle (Wiener Kreis). Other students of Mannoury were the philosopher and logician Evert W. Beth, the (chess) psychologist Adriaan de Groot and the mathematician David van Dantzig.
The Wikipedia said about his work : Mannoury’s main inspirations were G. W. F. Hegel, G.J.P.J. Bolland and F. H. Bradley. He was also inspired by the work of Friedrich Nietzsche, Baruch Spinoza, the French mathematician philosopher of science Henri Poincaré and the English positivism of Bertrand Russell. Mannoury combined a logical-mathematical way of thinking with a deep insight into the human soul.
The English Wikipedia did not mention his association with Lady Welby (27 April 1837 – 29 March 1912), a self-educated English philosopher of language, musician and water-colour artist, who had a major influence on the Dutch Significs.
Personal
On 8 Augustus 1907 he married Elizabeth Maria Berkelbach van der Sprenkel (1877, Den Helder) in Amsterdam. They got three daughters and a son named after his brother Jan (26 Aug 1909 14h30 Helmond, BC), who became on 4 July 1947 a PhD jurist publishing about social matters.
Mannoury, having faced the threat of poverty in his youth, became a very socially-involved person. In 1900 he joined the Labour party SDAP. He was one of the founders amd bpoard-members of the Sociaal-Democratische Partij in Nederland (SDP, 1909), the predecessor of the Communist Party in Nederland (CPN, 1918). His criticism on the expulsion of Trotsky, led to his own removal from the Dutch Communist party (Nov 1929). After that he retreated from politics, like the other communist signific, the poet Herman Gorter.
He died 30 January 1956 in Amsterdam.

Link to Wikipedia