I touched the faceted glass, cool, but not cold. A floral-citrus aroma rose up, and as I took my first sip I marveled at how soft and delicate the carbonation was, the bubbles giving the flavors lift and energy without aggression.

This was beer the really old-fashioned way. Today most draft beers are injected with carbon dioxide, filtered and often pasteurized, stored in pressurized kegs and served through gas-powered taps.

But the beer I was served was unpasteurized and unfiltered. Like the earliest bubbly brews, it was naturally carbonated, or conditioned, in its cask by yeast transforming sugar into alcohol with a side of fizzy carbon dioxide trapped in the cask. And it was served by muscle power pumping the ale up from its cask into the mug.