**Jean Victor Poncelet** was born in Metz in the year 1788. Having excelled as a student while attending Metz Polytechnic School, Poncelet became known as an excellent mathematics teacher and was invited to serve as an engineer in the Napoleonic army. In 1812 Poncelet fought the French forces in Russia, falling prisoner. During the eighteen months of captivity, he began writing one of his most notable works: Projective Geometry, the theory in which Desargues and Pascal had taken their first steps in the century. XVII.

In 1814 Poncelet returned to France and from 1815 began to publish his creations in the "Annals of Mathematics". His early works dealt with polygons inscribed and circumscribed to a conic.

Poncelet's great work, "Essay on the Projectives of the Conic Sections", only appeared in 1820 and was further refined and reproduced two years later under the title "Treatise on the Projective Properties of Figures." In these works, Poncelet observed that certain properties of the figures remain constant when the figures suffer projection deformations. Poncelet was also the creator of polarity theory and the principle of duality, on which other mathematicians such as De Morgan, Whitehead, and Russell later developed their work. Finally, Poncelet reached the height of his creation when he established the concept of double or anharmonic reason. Based on this discovery, Klein was later able to unify the geometries into one, creating pan-geometry.

Poncelet died in 1867 in the same city where he was born.

Source: Fundamentals of Elementary Mathematics, Gelson Iezzi - Current Publisher