Projective geometry — the geometry of perspective, where parallel lines meet and measurement falls away — is one of mathematics’ most beautiful structures, and Derrick Norman Lehmer’s An Elementary Course in Synthetic Projective Geometry builds it from almost nothing: the single idea of one-to-one correspondence, developed step by step into the theorems of Desargues, Pascal and Brianchon.
Lehmer writes with the economy of a mathematician who trusts his reader, and the synthetic method — no coordinates, just incidence and reasoning — keeps every proof visible to the eye. Download the free EPUB and learn the geometry painters discovered before mathematicians did.