I came across this Zen Koan recently and thought it would make a good story prompt – perhaps along SF-nal themes of consciousness and perception. I believe it is attributed to (or about) Hui neng, the sixth and last Patriarch of Chan Bhuddism.
Anyway, here it is:
Two monks were watching a flag blowing in the wind.
One said, ‘The flag is moving.’
The other said, ‘The air is moving.’
A Zen Master overheard them and said, ‘Neither the flag or air move. It is your minds that are moving.’