German Chancellor Angela Merkel praised the "world renown" of German beer in Ingolstadt, at a celebration marking the 500th anniversary of the beer purity law. The age-old rule has remained a staple of beer production.

German Chancellor Angela Merkel addressed the guests on Friday, praising the brewers' ingenuity in combining the four ingredients to create countless kinds of beer.

German beers enjoy "world renown," she said.

Merkel also quoted religious reformer Martin Luther who said that "a person without beer has nothing to drink," and statesman Otto von Bismarck who stated that it was a "basic need to talk bad about the government when drinking beer."

In Germany rules are rules—and they even apply to something as fun as beer. The Reinheitsgebot, Germany's legendary beer purity law, turns 500 on April 23 in a sudsy celebration known as German Beer Day. Many Germans love the law, but others think it's an outdated relic that should be chucked.

Beer purity is only one part of the Reinheitsgebot story; protectionism, taxes, national pride and marketing all come into play.

People get well-dressed and go on parade to celebrate the 500th birthday of beer purity law, in southern German city of Ingolstadt on April 22, 2016. German beer purity law, one of the world's oldest food safety laws, limits the ingredients of the amber brew to just water, barley, hops and yeast.