Silvanus P. Thompson Quote

One other thing will the professed mathematicians say about this thoroughly bad and vicious book: that the reason why it is so easy is because the author has left out all the things that are really difficult. And the ghastly fact about this accusation is that — it is true!

Calculus Made Easy: Being a Very-Simplest Introduction to Those - Beautiful Methods of Reckoning Which Are Generally Called by the - Terrifying Names of the Differential Calculus and the Integral Calculus (2nd Edition), Epilogue and Apologue (p. 284)