It is a sultry evening, the 28th of July in 1654 in Paris. Blaise Pascal has risen from his sickbed to await the arrival of his friend Pierre de Carcavi (1600–1684).1 Carcavi is a fellow member of the Mersenne circle, a coterie of leading French intellectuals. Pascal awaits the latest news of recent scientific developments that Carcavi has gleaned from his contacts among the group. Recently turned 31, Pascal has always been frail and in precarious health, but his mental powers are legendary. A child prodigy, he published his first original mathematical paper on conic sections at age 16.

At 20, motivated by the desire to assist his father, then a tax collector in the city of Rouen, he began work on a mechanical calculator he dubbed the Pascaline, which he subsequently perfected and sold. Pascal has also studied physics and at the age of 24 authored a book about his experiments with vacuums that led to a famous dispute with René Descartes, the most celebrated French scientist and geometer of the era. Pascal argued that vacuums actually exist, an idea that Descartes scoffed at, quipping that the only vacuum in nature resided inside Pascal's head.

Pascal sometimes finds travel difficult and is grateful for the more mobile Carcavi's efforts to keep him current on the commerce of ideas. At last, his friend arrives and after a few comments about the weather and Pascal's health, the two begin to discuss what Carcavi has learned. Pascal is especially delighted ...

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