[A mathematician is a] scientist who can figure out anything except such simple things as squaring the circle and trisecting an angle.

Esar’s quip plays on a classic irony in the public image of mathematics: mathematicians are presumed capable of solving any problem, yet two famous “simple” geometric tasks—squaring the circle and trisecting an arbitrary angle with straightedge and compass—were long-standing challenges. Modern mathematics proved these are impossible under the traditional constraints (circle-squaring via the transcendence of π; angle trisection in general via algebraic field theory). The joke hinges on the mismatch between apparent simplicity and deep impossibility, and on how mathematical rigor can turn a seemingly elementary puzzle into a definitive “cannot be done.”