According to the Bavarian Reinheitsgebot, or Purity Law, of 1516, beer can be made with only three ingredients: water, hops, and barley. (Yeast was left off the list because brewers didn’t know it existed; beer was naturally fermented, like sourdough bread.) German brewers still observe a version of the Reinheitsgebot, but Belgian brewers, just across the border, have cheerfully renounced it. Their krieks, wits, lambics, and gueuzes are among the world’s most remarkable beers, yet they’re often made with fruits or spices, or fortified with sugar, to become as potent as wine.
In America, brewers have long followed the German model: our major industrial breweries were all founded by German-Americans. But Calagione and others have lately wandered over to the Belgian side—and kept on going.
Burkhard Bilger, “A Better Brew”, The New Yorker (24 November 2008), 90.