Omar Khayyam — known in the West mainly for the Rubāʿīyāt — was above all a first-rate mathematician. He classified the fourteen forms of the cubic equation and showed how to solve each one geometrically through the intersection of two conic sections. His work explicitly establishes a bridge between algebra and geometry that the canonical narrative attributes almost exclusively to 17th-century Europe. It is a major piece of the silenced corpus of medieval Islamic mathematics.