There are a few more translations here. The best, in my opinion, is the least literal, by Robert Bly:

From seeing the bars, his seeing is so exhausted
that it no longer holds anything anymore.
To him the world is bars, a hundred thousand
bars, and behind the bars, nothing.

The lithe swinging of that rhythmical easy stride
which circles down to the tiniest hub
is like a dance of energy around a point
in which a great will stands stunned and numb.

Only at times the curtains of the pupil rise
without a sound — then a shape enters,
slips through the tightened silence of the shoulders,
reaches the heart, and dies.

Panther was the name of the gunboat in the Agadir incident. How do I know this? Because I was told it wasn't important.  From a post last year:

Long ago, when an O-level was still an O-level, I had a history lesson on the Agadir Incident. My recollection is as follows:

“Bla bla bla bla …. and sent a gunboat, Panther – but you don’t need to remember the name of the gunboat …..bla bla bla.”

As the exam drew near, our history teacher tested us on the Agadir Incident. “Bla bla bla?” she asked. “Don’t know,” we replied. “And what was the name of the gunboat?” she asked, wearily. “Panther,” we chorused.

The name of the gunboat, Panther, was the one thing we didn’t need to know about the Agadir Incident. And to this day, it is the one and only thing I remember. The causes, the incident itself, its consequences, its significance, even the purpose and direction of the gunboat are all lost in the mists of time. But the name of the gunboat, Panther, will stay with me till my dying day.

I think this is human nature, not just my nature. Try not to think of a pink elephant. You can think about anything else, just not a pink elephant. See what I mean?