《太平广记·卷十九·神仙十九》
道士说： 你坐在那里凝神静心，排除所有的杂念，就像一棵无知无觉已枯死的树。到了那个程度，我就可以带你一同上路了。 
曰： 相公安神静虑，万想俱遣，兀如枯株，即可俱也。 
The Taoist priest said: Sit there, absorb your mind and calm your heart, and get rid of all distracting thoughts. Just like a dead and unconscious tree, if you can reach that state, then I can take you on the journey together.