Folklore tells of a town where everyone was a mathematician. Each person was an expert, whether in arithmetic, algebra, geometry or topology; thanks to this expertise, measurements were always very precisely measured, definitions very precisely defined and costs very precisely calculated. 

Yet, as a mathematician called Simplex discovered, just because people think they've got everything worked out, doesn't mean they won't find themselves confronted by new ideas...

A story about quadrilaterals, and the difference between knowledge and understanding.