The Greek philosopher Thales, who was born in the seventh century B.C. in the city of Miletus on the coast of ancient Anatolia, espoused the principle that water was the arche, or beginning, of all things. He also believed, incidentally, that the Earth was a flat disk floating upon the sea. And while he missed the mark about the shape of the planet, there can be little argument that Thales was correct about the importance of water for all living things. From the earliest grains of wheat cultivated in prehistoric China to the lifesaving wells and cisterns of the Swahili people of East Africa, and from opulent Mughal gardens to a king’s reservoir in Cambodia, the need to harness and manage water was a catalyst for many of the most innovative engineering solutions and most lavish displays of wealth and power envisioned and created by people of the past.