Look there, friend Sancho Panza, where 30 or more monstrous giants rise up, all of whom I mean to engage in battle and slay, and with whose spoils we shall begin to make our fortunes. For this is righteous warfare, and it is God's good service to sweep so evil a breed from off the face of the earth."

"Look, your worship,'' said Sancho. "What we see there are not giants but windmills, and what seem to be their arms are the vanes that turned by the wind make the millstone go."

It has been four centuries since Cervantes penned Don Quixote and finally, life is imitating art. The seemingly absurd plot device of one of Western literature's most acclaimed works -- the idea that windmills could be seen as monstrous giants -- has been reincarnated, in very literal ways, in the friendly, touristy, distinctly un-Spanish climes of Cape Cod, Mass.

The present-day controversy over windmills is as spirited and surprising as the one Cervantes conjured between Panzo and Quixote: One side sees windmills as a pragmatic way to provide the world with cheap, pollution-free electricity and help curb global warming. The other sees them as ugly beasts that can slay birds and sully pristine vistas. And then, of course, there are the people in between -- those who advocate wind power and the larger renewable energy movement, but caution that windmills can pose serious economic and environmental setbacks to the communities where they are located. Yet even these in-betweeners speak of windmills as threatening industrial machines -- a far cry from the eco-friendly, flower-power image most often associated with clean energy.

The great wind controversy has been churning ever since the 1980s, when a massive, 7,000-turbine wind farm in Altamont, Calif., was found to be a killing field for migrating birds. But now the controversy is reaching a crescendo, as energy company Cape Wind Associates LLC seeks to erect a phalanx of 170 40-story (400-foot-tall) wind turbines on Horseshoe Shoal, a shallow portion of Nantucket Sound, off the coast of Massachusetts.