Little regarded in his own time, Girard Desargues developed a treatise and theorem that formed the basis for the development of projective geometry, breaking with the straight Euclidian traditions that had informed geometry since the Hellenistic age. However, it was not until almost two centuries after his death that Desargues was rediscovered and his work on conic sectionsgained its rightful place in mathematics. Although there is scant knowledge about Desargues' personal life, it is recorded that he was, as an amateur mathematician, a member of a renowned group of Parisian mathematicians, and that his work influenced the young Blaise Pascal. An engineer and inventor, Desargues also developed a pump device and wrote on such practical subjects as stonecutting, the production of sundials, and music composition.

Desargues was born on February 21, 1591 in Lyons, France, one of nine children of Girard Desargues and Jeanne Croppet. The elder Desargues was a...