Jacob Steiner was one of the greatest contributors to projective geometry. Although he died 150 years ago, his name remains in mathematical theorems that he developed. He proved the Poncelet theorem, which says that all Euclidean constructions can be done with a straight edge and a single fixed circle.
He was born in a small town in Germany in 1796, and was something of a late starter in life, not learning to write until he was 14 years old, and not attending school until he was 18! However, this did nothing to stop the young Steiner’s talents and he showed great mathematical aptitude.
He moved to Berlin in 1821and began taking private pupils in order to support himself, while he found time to contribute to the newly founded Crelle’s Journal (the first magazine to be dedicated to the publication of maths). He had caught the eye of Jacobi and some other notable mathematicians, who recommended that he take on a chair of maths at the Berlin University, where he taught from 1834 until his health deteriorated.
Apparently, Steiner was not a big fan of algebra and analysis, but felt that geometry stimulated thought! He was a prolific mathematician, often working so quickly that he had no time to notate his proofs. As a result, many of his findings remained unproven for years to come!