I'm interested in why the Greeks discovered the conics and not until 2000 years later did Kepler discover their astronomical importance.
As I understand it, the Greeks only really studied pure maths and philosophy. They did almost no experiments, and the scientific method was unknown. Consider that until a few centuries ago a thrown ball was thought to fly diagonally up and then fall vertically, despite the fact that every single object ever thrown proves this wrong. Conic sections were studied as a mathematical idea, but until the idea of experimental science took off no-one even thought to apply them to the real world, especially not to abstract dots in the sky.