Among the sources that tell us about Pascal's life, the biography written by his elder sister Gilberte holds a special place. She wrote it in 1663, the year after her brother Blaise died, intending it as a preface to the publication of the Pensées. Yet it was not until 1686 that La Vie de Monsieur Paschal, escrite par Madame Périer sa sœur, femme de Monsieur Périer, conseiller de la cour des aides de Clermont took its place there. The text of this late edition probably differs from the version written immediately after the mathematician's death. The version "closest" to the original is thought to be the one held at the Bibliothèque Mazarine (manuscript 4546), which clearly records that Blaise Pascal wrote a Traité des sons at the age of 11:
"Once, by chance, someone struck an earthenware dish with a knife at the table. He noticed that it made a loud sound, but that placing a hand on it immediately stopped the sound. He wanted at once to know why, and this experiment led him to conduct many others on sound. He observed so many things that he wrote a treatise on the subject at the age of eleven, which was found to be remarkably well reasoned."
A missing source
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Unfortunately, the Traité des sons has not survived. Did the philosopher develop only a physical model? Did he discuss musical theory, which was then still taking shape? No one knows. But what we know of his family circle and cultural environment may help us understand the young scholar's approach.
When the treatise was written, in 1634, the Pascal family had only recently moved to Paris; the boy had spent his early childhood in Clermont, in the Massif Central. His father, Étienne (1588–1651), was one of the city's leading citizens.
