As we took off, the ground was wooly with evergreens, but it quickly became obscured in haze and mist, a roiling sea speckled with foam. Welcome clouds wiped away the memory of solid ground, leaving only a vague impression that something must lie below – but really I can’t be sure.

About an hour into the flight I looked out again and the sky had turned into a perfect dreamscape – a clean slate. The clouds formed a flawless, featureless white floor, the sky an infinite blue ceiling. Anything was possible. Anything could happen.