Bonnet, Pierre Charles

Denis Casabianca

1It was thanks to his friend Pierre Mussard, who was charged with finding a printer for L’Esprit des lois during the summer of 1747, that the Genevan scholar Charles Bonnet discovered “this amazing work”; his enthusiasm was immediate. The letter from Bonnet to Montesquieu on 14 November 1753 (OC, t. XXI) is famous because Bonnet’s formula was passed on to posterity: “Newton discovered the laws of the material world; you have discovered, sir, the laws of the intellectual world.” (“Newton a découvert les lois du monde matériel : vous avez découvert, monsieur, les lois du monde intellectuel”). While Montesquieu had some sympathy for Bonnet (you cannot but sympathize with someone who, like you, has problems with his eyes), he did not engage in a truly intellectual exchange with him; the perspective of the Genevan, who saw in him a model, was foreign to him. In November 1753 Bonnet sent his Recherches sur l’usage des feuilles dans les plantes [‘Research on the use of plant leaves’], which Montesquieu said he appreciated for its observations (Montesquieu to Bonnet, 20 February 1754, OC, t. XXI). Yet the Essai d’observations sur l’histoire naturelle (1719) exposes a thesis which is the reverse of the one that would be developed in Considérations sur les corps organisés (1762); Montesquieu was opposed to the theory of pre-existing germs and all finalism in physics. Bonnet inscribes his design as a naturalist in a perspective that integrates the concepts of Book I of L’Esprit des lois: he also intends to identify “relations”. But the modification to which he subjects the definition of laws (letter of 1 April 1754; Masson, t. III, p. 1500) reveals a difference in attitude: Montesquieu is attentive only to effects, and does not seek to discover an overall theory, whereas for Bonnet the plan of nature must be discovered in the effects of the divine plan. This difference is manifested in Contemplation de la nature (1764), the introduction of which echoes the first chapter of L’Esprit des lois. Bonnet keeps only the theological formulas with a Malebranchian resonance to them; he associates the idea of relation to the idea of chain and the form of the first chapter which imitated a chain of being. Bonnet’s Leibnizian approach finds in Montesquieu’s text formulas that could serve to justify an avenue of research opposed to his, a sign that the detours of the first book of L’Esprit des lois offers a thousand possibilities for deviant readings.


Denis de Casabianca, Montesquieu. De l’étude des sciences à l’esprit des lois, Paris: Honoré Champion, 2008.