The history of wind power shows a general evolution from the use of simple, light devices driven by aerodynamic drag forces; to heavy, material-intensive drag devices; to the increased use of light, material-efficient aerodynamic lift devices in the modern era. But it shouldn't be imagined that aerodynamic lift (the force that makes airplanes fly) is a modern concept that was unknown to the ancients. The earliest known use of wind power, of course, is the sail boat, and this technology had an important impact on the later development of sail-type windmills. Ancient sailors understood lift and used it every day, even though they didn't have the physics to explain how or why it worked. The first windmills were developed to automate the tasks of grain-grinding and water-pumping and the earliest-known design is the vertical axis system developed in Persia about 500-900 A.D. The first use was apparently water pumping, but the exact method of water transport is not known because no drawings or designs -- only verbal accounts -- are available. The first known documented design is also of a Persian windmill, this one with vertical sails made of bundles of reeds or wood which were attached to the central vertical shaft by horizontal struts (see Figure 1a). A 19th Century American approximation of this panemone device is shown at the left (Figure 1b). Grain grinding was the first documented wind mill application and was very straightforward. The grinding stone was affixed to the same vertical shaft. The mill machinery was commonly enclosed in a building, which also featured a wall or shield to block the incoming wind from slowing the side of the drag-type rotor that advanced toward the wind. Vertical-axis windmills were also used in China, which is often claimed as their birthplace. While the belief that the windmill was invented in China more than 2000 years ago is widespread and may be accurate, the earliest actual documentation of a Chinese windmill was in 1219 A.D. by the Chinese statesman Yehlu Chhu-Tshai. Here also, the primary applications were apparently grain grinding and water pumping.