104 Chapter 7
The last of six children born to a provincial laboring family, Mersenne did not come
from the privileged world of Descartes, yet he came to share its intellectual and cultural
milieu. Though they overlapped at the same Jesuit school, there remains no record of
any contact between them then; Mersenne was eight years older and the Jesuits took care
to separate boys of different ages. After further studies in Paris, at age twenty-three
Mersenne joined the Franciscan Order of Friars Minor, known as the Minims, then con-
sidered the most severe monastic order in Western Christendom. He spent most of
his life in that order ’ s monastery in Paris, but through friendship and an immense cor-
respondence, he reached out to a vast array of scholars across Europe. Descartes was
only one among a group of correspondents with whom Mersenne maintained a particu-
larly strong contact. In that era before academic journals, Mersenne ’ s letters served to
disseminate and exchange views so well that his correspondents were effectively publish-
ing their letters to him. He did not scruple to hide what he learned because, for him,
dissemination and discussion of important new findings far outweighed issues of priority.
His activities constituted a veritable “ Acad é mie Mersenne ” he organized and conducted
through his correspondence, which led to the formation of the French Acad é mie des
Sciences in 1666.^4
Mersenne ’ s own intellectual journey took him from conventional adherence to geo-
centric cosmology to gradual acceptance and advocacy of the new Copernican views,
even against the opposition of the Roman hierarchy. In his voluminous commentary on
Genesis, Quaestiones in Genesim (1623), his first published work, he cited the eccle-
siastical condemnations of 1605 and 1616 against Copernicus and concluded that he
“ could not demonstrate that the center of the universe is not our earth ... whatever the
explanation of Aristarchus of Samos and Copernicus after him. ”^5 His phrasing suggests
that, though he had some sympathy for the Copernican view, he could not demonstrate
it to his own satisfaction, at least to the point of holding it publicly in the face of
ecclesiastical opposition. But as he assembled the materials for his work on universal
harmony, Mersenne gradually moved closer and closer to the Copernican position,
moved by musical arguments he discusses in his Trait é de l ’ harmonie universelle
(1627), a trial run for the magnum opus he produced a decade later. He locates the
technical astronomical issues within the context of the relation between musical con-
sonances, the heavens, and the planets.
Mersenne begins with the Platonic account and places himself with those who believe
in the auditory reality of the heavenly music. We cannot hear this heavenly music, “ for
we are accustomed to it from the wombs of our mothers. Sometimes the sound is too far
from us, too low, too high, or too great to be heard, ” as with the extremely quiet sounds
“ which ants and other little animals make. ”^6 Having marshaled the classical lore, he asks
“ if Johann Kepler has alighted on more than Robert Fludd concerning celestial harmony. ”
Mersenne phrases the debate between Copernicus ’ s champion, Kepler, and the geostatic
traditionalist Fludd, with Brahe providing “ the most correct observations that we have. ”