The most famous classic of Chan Buddhism (Chinese Zen) is the Platform Sutra 六祖壇經. The sutra presents the teachings of Huineng 慧能 (638-713) [However, the text went through many revisions and the ten chapter edition that is currently taken as authoritative actually dates from 1291]. The most read section is the first chapter which records the competition for succession to Hongren 弘忍, the fifth patriarch. There were two contenders, Huineng and Shenxiu 神秀. The competition was conducted by the writing of a verse. The verse should show the author's understanding of the fundamental meaning of Chan.
The verse of Shenxiu is as follows
The body is the bodhi tree,
The mind like a mirror bright.
Ceaselessly, diligently, wipe the mirror
Let no dust alight!
Huineng then wrote a rejoinder to this verse
Fundamentally bodhi has no tree,
The mirror has no stand.
Originally there is not a single thing
Upon which dust could land.
These two verses are of enormous importance in understanding the deep meaning of Buddhism. On the one hand, there is the work of cleaning the mind. On the other hand, there is the realisation that mind itself cannot be contaminated. All delusion is adventitious and ephemeral. To not work at the practice is to sink further into delusion, yet to work too hard at the practice is to take delusion too seriously. What is one to do?
All Buddhist practices seek to cut through this seeming contradiction in one way or another. We could say that if Shenxiu's verse is the thesis, Huineng's is the antithesis; and the task is to find the synthesis.
Whether we see a Bodhi Tree
Or a mirror bright
When we welcome everything
Dust will shine with light.