René Descartes (1596-1650) is one of the most important figures in Western philosophy and mathematics. With his famous statement Cogito ergo sum, he raises for the first time the problem of the relationship between matter and spirit, soul and body, while Cartesian coordinates made it possible to conquer the physical space.
But Descartes also had a secret side to his life. He was a member of the Rosicrucian Brotherhood and kept a secret notebook, now lost, where he wrote his notes in a coded language. After his death, Leibniz, one of the greatest mathematicians of all time, went to Paris in search of this notebook. Eventually, he found it. It had passed into the possession of Claude Clerselier...
Why did Descartes keep a secret notebook? What was its content? The answers to these questions will lead the reader on an exciting journey of acquaintance with one of the great figures who shaped the science of Western Civilization.