> What's this delta-epsilon proof of a limit all about and why do I care? I remember a test in high school where the bonus question was a delta epsilon proof.

> What's this delta-epsilon proof of a limit all about and why do I care? I remember a test in high school where the bonus question was a delta epsilon proof. It was the only question I got full marks on. On all the other 'easy' ones where you had to memorize the derivatives of fundamental functions (sin, cos tan...) I made many mistakes. The teacher wrote: "You understood the most difficult part, as usual..." I got poor marks on the test, but it's one of my proudest memories as a math student.