Yongjia Xuanjue (665 – 713 CE) was a Chinese Buddhist monk of the Chan school, who is now best remembered as the author of the Song of Enlightenment, often identified by its Japanese name, the Shodoka. The verse below is from that collection, which is widely studied by Zen students to this day. Yongjia is said to have passed away while meditating.
No bad fortune, no good fortune, no loss, no gain;
Never seek such things in eternal serenity.
For years the dusty mirror has gone uncleaned,
Now let us polish it completely, once and for all.
Translation Robert Aitken