A Koan is one of the most meaningful practices in Zen Buddhism. Unfortunately, people typically think of a koan as nonsensical. However, the koan has another purpose in disciple's training which is to move beyond the accepted concepts of meditation and challenge the disciple's search for the answer. But, of course, there is no one correct answer.
With that brief introduction, here is one of my favorites koans because it fits in so well with neurophysics and (spoiler alert) quantum physics.
Who is the Great Magician that makes the grass green?
Check the next blog or two for an answer that may make you re-evaluate your position in the cosmos. Then, when you think you have the answer and are sure of it, you might ask yourself if you are sure enough to be unsure. It is that moment of doubt stopping to think things through. In modern psychology, it might be called a transderivational search and that moment is the driving dynamic behind the koan.