His latest, ''Descartes' Secret Notebook," is a first-rate suspense story. It begins with an unsuspecting Aczel setting out to research the life and work of Renee Descartes when he finds the philosopher/mathematician kept a secret notebook. Aczel's project turned into a detective adventure, revealing occult science, a secret brotherhood, political and religious controversies, a locked box, romance, obsession, a jealousy that may have had fatal consequences, and Descartes's purloined skull.
Best known in nonmathematical circles for his mind-body philosophical statement ''I think, therefore I am," Descartes (1596-1650) was born in west-central France. His had a privileged upbringing, and the wealth he inherited afforded him the freedom to pursue his interests, including serving as a gentleman soldier, traveling, and, of course, studying and thinking deep thoughts.
The deepest of these thoughts Descartes recorded in a special notebook. ''He began to believe that mathematics held the secret to understanding the universe. . . . He worked out ancient Greek problems in geometry, but he soon concluded that the power of geometry transcended pure mathematics: geometry held the secret to all creation," writes Aczel.
Not only did he keep this journal hidden in a locked box, Descartes encrypted his entries, using symbols, number sequences, and obscure figures to ensure that the nature of his work would be disguised if his notebook was ever discovered.
A quarter of a century after Descartes died,Gottfried Wilhelm Leibniz, 30, whom history would recognize as one of the greatest mathematicians of all time, came to the end of his 3 1/2-year quest to find the hidden writings. The caretaker of Descartes's trove allowed Leibniz to copy only 1 1/2 pages of them, but Leibniz nevertheless was able to decipher the entire notebook. As promised, he remained silent about his findings.
