From the DZ:

The sage sees how to stop clinging
While all others find this very hard.
If you can see through joy and sorrow,
Then you too will glimpse the great peace.

- Perfection of Wisdom

I have been having a hard time letting my thoughts float in and out during zazen recently. I seem to grasp whatever comes into my head and process it with thought until I consciously expel it and start that process over with something else. The idea of zazen, as I understand it, is to have direct experience with the life force that precedes thought entirely. I may have done this on a few occasions -- I'm not exactly sure -- but it's been difficult to achieve that state of mushotoku mind, where I have no expectation of gain and where I just let thoughts drift like clouds across the sky. However, on those few occasions, I have felt my mind break through its boundaries and become spacious and somehow connected with life, the universe, and everything. Or maybe somebody put something in the water.