Tuesday, January 20, 2009

Descartes' Secret Notebook

A True Tale of Mathematics, Mysticism, and the Quest to Understand the Universe

Descartes continues to fascinate us not just because he was a titan. He lived in a strange and unruly age, and led the sort of life one would not expect of a philosopher. He was a gentleman soldier and intellectual tourist whose life continues to provide a rich field of speculation for writers three centuries after his death.

The raison d'etre of this new biography is a secret notebook found after Descartes' death. It was written in code because (argues the author) it contained information that Descartes felt would endanger his life should the Inquisition get wind of it.

Leibniz apparently cracked the code but kept the secret to himself. (He was preoccupied by a feud with Newton over calculus.) Not until 1987 was the code deciphered and made public. Descartes had discovered a formula regarding geometric figures that is a property of space itself, and a foundation for the science of topology. A century after his death this formula was rediscovered by the Swiss mathematician Euler.

Descartes' Secret Notebook is smoothly and gracefully written, and its author, Amir Aczel, who is himself a mathematician, concisely explains some of the esoteric aspects of Descartes' work. Best of all are the final three chapters, which describe events after Descartes' death, including the involvement of Leibniz.


Descartes was a Catholic and took great pains not to fun afoul of the Church, as Galileo had. Aczel quotes him as writing, "Fear of God is the beginning of wisdom." How ironic then that another Frenchman, 300 years later, would take a very different view. Sartre, an atheist, writes in Nausea, mocking Descartes:

I am, I exist, I think, therefore I am; I am because I think, why do I think? I don't want to think any more, I am because I think that I don't want to be, I think that I...because...ugh! I flee.

Both men lived through times of great upheaval in Europe -- Descartes the Thirty Years War and Sartre WW2, during which he spent nine months as a POW.