Mathematics as we know it today, with theorems and proofs, began with the great Greek mathematician Thales of Miletus (ca. 624–548 BCE). Miletus was among the first free city-states within the larger Greek empire, which spanned much of the eastern Mediterranean from Anatolia to the south of Italy and Egypt, including the islands in between. Lying on the coast of Anatolia, Miletus was one of the oldest and most prosperous Greek settlements of the time. Thales is often called the first philosopher. He is also known for his famous saying “Know thyself,” which was even engraved on the stone entrance to the cave of the Oracle of Delphi, a sacred site where the Greeks sought counsel from their gods. Additionally, Thales was one of the Seven Sages of Greece, though according to the historian Plutarch, he surpassed the others. In his book on Solon, another of the Seven Sages, Plutarch says this about Thales: “He was apparently the only one of these whose wisdom stepped, in speculation, beyo...