The jurist, mathematician, geometer and physicist Claude Mydorge (1585–1647) was fortunate enough to be born into a wealthy family: his father, Jean, was a councillor at the Parlement and a judge in the Grande Chambre, while his mother belonged to the Lamoignon family, one of the richest in France. Their son Claude was therefore soon appointed a councillor at the Châtelet. But rather than become a member of the Parlement, he chose to purchase the office of treasurer of the "généralité of Amiens," which covered what is now Picardy. A généralité was then an administrative unit under the authority of a collector-general (hence the name "généralité"). Since 1577, this official had been assisted by a treasurer whose largely honorary duties were far from demanding. Claude Mydorge was thus able to devote most of his time to the study of science, just as he wished.
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A mysterious acronym
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Mydorge promptly began studying geometry and physics, with a particular interest in optics, from which he derived a whole series of results on conic sections. This research appeared in his 1631 work Prodromi catoptricorum et dioptricorum sive Conicorum operis ad abdita radii reflexi et refracti mysteria praevii et facem praeferentis, whose title clearly refers to the cone (conicorum) and the laws of reflection (reflexi) and refraction (refracti). In it, he simplifies many of Apollonius of Perga's proofs while developing powerful new ideas, notably introducing the concept of "deforming a figure." Among other results on deformations of conic sections, he shows how a circle can be deformed into an ellipse.
His technique was later taken up by Philippe de La Hire and Isaac Newton, and subsequently by Jean-Victor Poncelet (1788–1867) and Michel Chasles (1793–1880). Chasles made no secret of his admiration for his predecessor. In his Aperçu historique sur l’origine et le développement des méthodes en géométrie, published in 1837, he wrote: "Unlike Desargues and Pascal, Mydorge's main purpose is not to derive the properties of conics from those of the circle, either through perspective or by continually considering the cone in which they originate. His work is written in the style of the Ancients; yet, by making greater use than they did of the cone, he can encompass in a single proof propositions that required three proofs from Apollonius, thereby greatly simplifying the subject."
