I love this idea, that nature dreamed up the same kind of sleep in both humans and birds, fostering the growth of big brains in creatures so far apart on life’s tree.

It seemed to Whish that any potential crack was worth trying to open,” wrote the scientists. “Even a person’s face was not sacrosanct. He would fly to the face and clutch hole on the nose arch. He would then hang upside down and peer into the nostrils.

If one of the species you’re using in your experiment fails every test you give it, the problem may be you, the researcher, not the animal. You may have failed to understand what is relevant to the way a bird sees the world.

They circle; now dense like a polished roof, now disseminated like the meshes of some vast all-heaven-sweeping net, now darkening, now flashing out a million rays of light . . . a madness in the sky