Feathers

Engineers call feathers the most efficient insulating material ever discovered.  They've inspired legends and literature, from Icarus to Shakespeare.  They've inked documents from the U.S. Constitution to the novels of Jane Austen.  They've decorated queens, jesters, plague doctors, Aztec priests and the fabled birds of paradise. They silence the flight of owls, give shimmer to hummingbirds, and keep penguins dry below the ice.   They are at the root of biology's most enduring debate: whether birds are dinosaurs.  Yet their story has never been fully told.
                     From "Feathers", by Thor Hanson

P.S.  My Cheerful Challenge will resume Monday when the trial does.