This is what changed after Newton and Leibniz. They independently discovered and proved a fundamental theorem that made such problems routine. The theorem connected areas to slopes and thereby linked integrals to derivatives. It was astonishing. Like a twist out of a Dickens novel, two seemingly distant characters were the closest of kin. Integrals and derivatives were related by blood.
I love this! Hahaha. Twist in a dickens novel = FTC
