The work consists of six lessons popularizing the knowledge of René Descartes and Nicolas Copernicus, taught through conversation with a Marquise, spread over six evenings and preceded of a preface and a dispatch To Monsieur L*** .

[citation needed] It is an early exposition of cosmic pluralism, the idea that the stars are distant suns which might have their own planetary systems, including the possibility of extraterrestrial life.

[citation needed] In the preface, Fontenelle suggests that the offered explanation should be easily understood even by those without scientific knowledge, and he specifically addresses female readers.

The book itself is presented as a series of dialogues between a gallant philosopher and a marquise, who walk in the latter's garden at night and gaze at stars.

[citation needed] It is significant that the Marquise is an intelligent and curious thinker, able to understand complex ideas and suggest her own, subverting the wide-spread misconception that women were not capable of comprehending higher concepts.