"Look, your worship, said Sancho; what
we see there are not giants but
windmills, and what seem to be their
arms are the sails that turned by the
wind make the millstone go."
- Miguel de Cervantes, Don Quixote
In order to efficiently grind significant amounts of grain into flour one must first learn to harness the powers of that most tireless turner of the grindstone: the wind. Windmill Theory allows you to construct Windmills.