Beginning in 3500 BC, humanity developed a system of counting to track business deals and to measure land. By the middle of the third millennium BC, the Egyptians could calculate the area and volume of simple geometric shapes using a base-10 system. This laid the foundation of geometry. With geometry, the Greeks revolutionized mathematics. This conceptual approach - with its postulates, proofs, and theorems - provided a foundation for logic and argument for the next two thousand years.