Book Review: Descartes's Secret Notebook by Amir D. Aczel

Descartes’s Secret Notebook

Author: Amir D. Aczel

Publisher: Crown Publishing Group

Date of Publication: October 10, 2006

Pages: 288

            This fascinating and highly readable book is part biography, part mystery and part treatise on philosophy and mathematics.  Rene Descartes lived from 1596 to 1650.  His life was one of adventure and discovery.  His philosophy was hotly debated at the time and his discoveries in mathematics were and are regarded as genius.  This author tries to add another layer to the legend by examining a purported secret notebook, long lost but copied in part by German mathematician Gottfied Wilhelm Leibniz after Descartes’ death.

Rene Descartes was born to a wealthy family in the town of Chatellerault, France.  He was baptized in the Roman Catholic Church and remained a devout and loyal Catholic his entire life.  His mother died in childbirth a year later and Descartes’ own health as a youth is described as poor.  He received what we all recognize as the great advantage of a Jesuit education at what is now a military academy in the town of La Fleche, the Prytanee National Militaire.  He then received a doctor of laws degree in 1616 and moved to Paris.  In Paris he developed his interests in mathematics, physics and eventually, philosophy.  He also traveled extensively to the Netherlands and Denmark.  His health as an adult was much improved and he never lost his interest in the military.  He even joined the army of Maximilian, the duke of Bavaria, at the beginning of the Thirty Years War.  It was during this time as a volunteer soldier in Maximilian’s army that he began his studies and interpretations of geometry and science.  Eventually Descartes settled in Holland where his Cartesian philosophy created controversy.  Everyone is familiar with “I think, therefore I am” (or “Cogito, ergo sum”), but the basis for this definitive statement is a very concise, even mathematical, proof of the existence of God.  This was the time of turmoil between the Roman Catholic Church and the Protestant denominations and the acceptance of Descartes’ reasoning was not universal. He was even accused of the serious charge of atheism despite his devout Catholic heritage and practice.  Eventually Descartes became the philosophy instructor for Queen Christina of Denmark.  There were jealousies between Descartes and the Queen’s other instructors as Descartes quickly became the young Queen’s favorite.  The fact that the others were strict Calvinists played a role.  Descartes died under somewhat suspicious circumstances in Sweden in 1650.  There are suggestions that he may have been poisoned by a rival.  His belongings were catalogued and shipped to relatives in France.  Eventually many of his original documents, including the secret notebook alluded to in the book’s title, disappeared.

The secret notebook was a private notebook which Descartes never intended to publish.  He used codes and symbols that were indecipherable for centuries.  Part of this notebook was copied by Leibniz shortly after Descartes death and that is all that remains of the document.  Some historians felt that this notebook represented Descartes membership in a secret society, the Rosicrucians.  Others felt that Descartes had discovered the origins of the universe.  It was not until 1987 when Pierre Costabel published his definitive analysis of Leibniz’ copy of Descartes’ secret notebook that the true meaning of the secret notebook was revealed.  Descartes had discovered a coveted formula for a rule which governs the structure of three dimensional solid objects.  This was mystery which had eluded Plato and the other Greek geometricians as well as all other mathematicians in history.  He had discovered the modern field of topology centuries before its time.  The reason he repressed this discovery was because it supported Kepler and Copernicus and their analysis of planetary motion around the sun.  The timing of this coincided with the Roman Catholic Church’s prosecution of Galileo for heresy.  Descartes, the loyal Catholic, did not want to suffer the same fate.

There are many interesting side stories in this tale, including the simultaneous discovery of the calculus by Newton in England and Leibniz in Germany.  There may be a connection between these two men which would be, of course, Rene Descartes.  Descartes private life is examined as far as historical facts allow, including a possible marriage to a servant girl and a relationship of some sort with Princess Elizabeth of Bavaria who was living in exile in Holland at the same time as Descartes.  The exact relationship between Descartes and Queen Christina is a mystery as well.  At about age 40 Descartes noticed his first grey hairs.  He felt this was a sign of impending death and began dissecting animals by the hundreds in an attempt to discover the secret to a prolonged life.  He greatly altered his diet, becoming basically a vegetarian.

This is a fascinating book.  I remembered very little of Descartes from my Philosophy 101 class and this book made me wish I had paid more attention.  The historical aspects of this time are equally absorbing.  The author makes the mathematics understandable (not an easy task in my humble opinion) and the philosophy enjoyable.  

Rene Descartes
1596-1650