A story of Bodhidharma and Milarepa meeting

The excerpts of this story is from yogichen.com

… When we say there is no practice in Chan, this means one has learned to box without fists. Just like a bird which flies through the sky but leaves no tracks. When you get the Chan function, then you can enter the world and say I have no need to renounce, but not before. It is possible to find the truth in each blade of grass, i.e., whorehouses, gambling casinos, theaters, and bars, etc. But it is best to keep a little distance at first to make your comprehension very sharp. When you come back every blade of grass will bow down to you.