The swamp had never known structure. The tadpoles learned to swim by sinking. The herons taught themselves to stand on one leg through trial and error (and many wet falls). The beavers built dams that were structurally sound but aesthetically offensive. It was chaos.

His first student was a cynical bullfrog named Gerald. Gerald had a deep, rumbling voice and a habit of eating anything that flew too close.

He never did fly. But every spring, when the new eggs hatched, the first sound the ducklings heard wasn’t their mother’s call. It was the gentle tap-tap-tap of a wooden ruler on a hollow log, and a familiar, gravelly voice saying:

One evening, as the sun bled orange into the water, Gerald the bullfrog—now Professor Gerald of Amphibian Kinetics—sat beside Beaker on the sunning deck.