Try imagining one little bird sitting on a branch, singing in a clear, high voice. He has a pretty little beak and colorful feathers. You stare at him, enchanted; but as soon as you breathe, he flies away, leaving only the bare branch, and a few dried leaves fluttering in the breeze.” The Professor pointed out at the dark garden, as if the bird had really just flown away. The shadows seemed deeper and longer in the rain. “Yes, 1 – 1 = 0. A lovely equation, don’t you think?”

