The body is the bodhi tree
The mind is like a bright mirror’s stand.
At all times we must strive to polish it
And must not let dust collect.
- Hongren
Bodhi originally has no tree
The bright mirror also has no stand
Fundamentally there is not a single thing
Where could dust arise?
-Shenxiu
From what I remember (I am not going to look it up) this poem is actually two poems which were written when a new abbot was required for a monastery and the monks were required to write a verse to prove themselves worthy of the post. The first one was written by the head monk (the natural successor). It stresses the need for practice and the discipline and effort needed to maintain mind clarity.