In the late 19th century, Karl Weierstrass invented a fractal-like function that was decried as nothing less than a “deplorable evil.” In time, it would transform the foundations of mathematics.

Koeno Gravemeijer, Michiel Doorman, Context Problems in Realistic Mathematics Education: A Calculus Course as an Example, Educational Studies in Mathematics, Vol. 39, No. 1/3, Teaching ... In light of ...