The best books on moral and political subjects are distinguished by an arrangement and precision which he traces to the esprit geometrique characteristic of Descartes.

[Footnote: Sur l'utilite des mathematiques el de la physique (Oeuvres, iii.p.6, ed.

1729).] Fontenelle himself had this "geometrical mind," which we see at its best in Descartes and Hobbes and Spinoza.
He had indeed a considerable aptitude for letters.

He wrote poor verses, and could not distinguish good poetry from bad.

That perhaps was the defect of l'esprit geometrique.