The Galileo Project
site map

Crousaz, Jean-Pierre de

1. Dates
Born: Lausanne, 13 Apr. 1663
Died: Lausanne, 22 Feb. 1750 (NBG gives his year of death as 1748)
Dateinfo: Dates Certain
Lifespan: 87
2. Father
Occupation: Aristocrat
Abraham de Crousaz was "colonel lieutenant de Leurs Excellences de Berne." He belonged to one of the oldest and most noble families of Lausanne.
In view of all the information on Crousaz's life, including estates he inherited, he had to have been reared in conditions at least affluent.
3. Nationality
Birth: Switzerland
Career: Switzerland, Netherlands, Germany
Death: Switzerland
4. Education
Schooling: Lausanne, Geneva, Leiden
He studied philosophy and reformed theology at the Academy of Lausanne, where he matriculated in 1676, and then at the Academy of Geneva. "Academy" is an ambiguous word, not always used in the same way, but I find the Academy of Lausanne described as a school of High Studies (Haute Études), which I equate with university, even though it did not acquire the legal status of a university until the end of the 18th century. I assume that the Academy of Geneva was of similar status. I categorize both as universities.
At age 19, dissatisfied with the conservatism of education in Switzerland, he left for a period of study in Leiden. Although I did not meet explicit mention of a degree, it seem implicit in all of Crousaz's following career.
5. Religion
Affiliation: Calvinist
Crousaz was an innovator in a traditional setting, and he generated doubts about his own orthodoxy. In his old age, however, he was defending Christianity against the esprit philosophique (which meant, for him, primarily Leibnizian fatalism). He also issued a refutation of Collins' deism.
6. Scientific Disciplines
Primary: Mathematics, Natural Philosophy
Subordinate: Mechanics
His Commentaire sur l'analyse des infiniment petits, appeared in 1721, made him famous.
He also published Logique, which had many editions, Traité du beau and several other works on philosophy, mathematics, and education, but these do not appear to have pertained to science.
He received from the Académie des Sciences of Paris the first prize in the annual competition for a memoir on the theory of movement in 1720, and in 1722 a prize on the causes of elasticity from the Academy of Bordeaux. He later won two more prizes from the Academy of Bordeaux on similar topics in what I would call natural philosophy--in effect Cartesian mechanical philosophy. In Lausanne he was the voice against Scholasticism and for the new mechanical (again, Cartesian) philosophy. At about the age of eighty he finally converted to Newtonianism!
7. Means of Support
Primary: Personal Means, Patronage, Academia
Secondary: Church Life, Schoolmastering
In Crousaz's case, more so than in most others I have seen, it is very difficult to decide on the relative importance of the different sources of support. All five contributed.
1684-99, Crousaz was deacon of Lausanne. This was a church position; it involved preaching. To supplement his meager income during this period, he taught a course in "raison" (Greek, Latin, philosophy, and mathematics) for eight or ten hours per day, and used his home (in a manner familiar in the age) as a hostel for his students.
Professor of philosophy and mathematics at the Academy of Lausanne, 1700-1724. He also taught privately (as he continued to do through much of his life).
Rector of the Academy of Lausanne, 1706-1708, and 1722- 24. Crousaz was caught in what I would call a fundamentalist reaction in Lausanne and became an object of attack. Also feeling hemmed in by the provinciality of Lausanne and longing to participate more fully in the wider intellectual life of which he now knew, he chose to leave Lausanne.
Professor of philosophy and mathematics at the University of Groningen, with a salary of 1500 florins, 1724-1726. In Groningen he also gave private lessons and kept students in his home.
Governor of Prince Frederick at the house of Hesse- Kassel, 1726-1732.
Received a pension of 800 écus for life from the Landgrave of Hesse, 1733. This was less a sign of affection then a device to terminate Crousaz's relation with the court.
Professor of philosophy at the Academy of Lausanne, 1738- 1749.
Although I find it impossible to assess with assurance, it is clear that Crousaz drew part of his sustenance from the family estate. In his will he left a number of vineyards, surely his own inheritance, to his heirs.
8. Patronage
Types: Court Official, Government Official
La Harpe speaks explicitly of Crousaz's protectors and patrons in Bern, the seat of the government of his canton, who controlled the academy in Lausanne. Crousaz dedicated books to the governors of the academy.
Crousaz dedicated his first book in mathematics (the Traité d'arithmetique, 1715) to Abbé Bignon in Paris. (I cannot categorize Bignon as an ecclesiastical official; he was a governmental one.) In the early 20's, as he became desperate to leave Lausanne, he dedicated his Traité de l'education to the Princesse de Galles (does this mean Princess of France?). He dedicated his Traité d'algebra to Reaumur. His efforts were not confined to France. It appears to me that he tested all the avenues of patronage over much of northern, Protestant, Europe and of France. (see La Harpe, pp. 58-66.)
About the time Crousaz was leaving Groningen, he received offers from the court of Orange to teach Prince William and from the King of Poland for a position at Halle.
He stayed in the house of Hesse-Kassel for 7 years to direct the education of the young heir, Prince Frederick. Before he left the house, the Landgrave of Hesse granted him a life pension.
9. Technological Involvement
Type: None
10. Scientific Societies
Memberships: Académie Royal des Sciences, 1725-1750
Associate member of the Académie des Sciences.
Associate member of the Académie des Sciences of Bordeaux, 1735-1750.
About 2000 letters were sent or received by him. In his correspondence with Reaumur, he discussed natural history, particularly certain shellfish found near Neuchatel; with Abbe Nollet, it was electricity; with Maclaurin optics. Among his correspondents were also Maupertuis, Jacques Cassini, Fontenelle, Bernoulli, and Mairan, who was his closest confidant. Most of these letters are in the archives in Lausanne, but smaller numbers are spread over much of Europe.
  1. E. de La Harpe, Jean-Pierre de Crousaz et le conflit des idees au siecle des lumieres, (Geneva, 1955). [B4651. C94 L18]
  2. "Eloge de Crousaz", Histoire de l'Académie des Sciences, 1750, pt. 1, pp. 258-74.
  3. Nouvelle biographie générale, 12, 546-7.
Not Available and Not Consulted
  1. Eugene Secretan, Galerie suisse, Biographies nationales..., 1, (Lausanne, 1879), pp. 591-599.
Compiled by:
Richard S. Westfall
Department of History and Philosophy of Science
Indiana University

Note: the creators of the Galileo Project and this catalogue cannot answer email on geneological questions.

©1995 Al Van Helden
Last updated
Home | Galileo | Biography | Chronology | Family | Portraits |
Science | Christianity | Library | About | Site Map | Search

Please note: We will not answer copyright requests.
See the copyright page for more information.