Zen Master Kyōgen Chikan was once asked by a monk, "What is the Way?"
The Master answered, "The singing of dragons among withered trees."
The monk replied, "I don’t understand."
The Master said, "Eyeballs in a skull."
A monk later asked Master Sōzan, "Can anyone hear the singing of dragons among withered trees?'"
Sōzan replied, "There is not one person on the whole of the great earth who does not hear it."
The monk asked, "What verses does a dragon sing?"
Sōzan replied, "Even without knowing what those verses are, those who do hear it bemoan the fact that others do not."
Everyone can hear the dragon's roar because it exists everywhere. The dragon's roar is the expression of one's innate Buddha nature, and Buddha nature is in everything. There can be no escape from it. As for the withered tree, it shouldn't be mistaken for a dead tree. "Withered trees" are a metaphor for someone who has reached a deep level of meditation, a person whose passions have all but disappeared. "Withered trees" abound with life and celebrate each and every spring with new foliage. It's just that few have realized this.
John Daido Loori points out that those who can see through to the point of this koan and make it their own will have the daragon's roar for their own voice and will be able to make use of it among the ten thousand things. If however, you are unable to perceive it, then the worldly truth will prevail and everything will appear to be an impenetrable barrier.
Zen Master Dogen once said that he would have liked to have asked Sōzan, "Putting aside for a moment your remark about there being not one person on the whole of the great earth who have not heard it, tell me, in the time before the whole earth sprang into existence, where was the roar of the dragon then? Speak up! Quick, quick!"