"What is Zen?" STOP.The mere fact that you ask reveals you as one of the unenlightened. First, embrace the fact that you are but a tiny atomic chrysalis in the midst of a universe-sized butterfly, flapping, musically, free. Next, consider a koan— together, with us, as one.
Subhuti was Buddha's disciple. He was able to understand the potency of emptiness, the viewpoint that nothing exists except in its relationship of subjectivity and objectivity.
One day Subhuti, in a mood of sublime emptiness, was sitting under a tree. Flowers began to fall about him.
"We are praising you for your discourse on emptiness," the gods whispered to him. "But I have not spoken of emptiness," said Subhuti.
"You have not spoken of emptiness, we have not heard emptiness," responded the gods. "This is the true emptiness." And blossoms showered upon Subhuti as rain.
The enlightenment: There was a big sale on flowers, and at some point you have to get rid of all those flowers.