Su Shi's poem, Dogen's commentary

The sound of the stream – Buddha’s long broad tongue,
The form of the mountains – his pure body.
Ten thousand verses through the night,
In the morning, how will I explain them to others?

by Su Shi

Dōgen’s commentary:

On the night that Su Shi was enlightened, he had just heard his master’s teaching about insentient beings preaching the Dharma. His teacher’s words did not instantly awaken him, but when the sound of the stream hit him, it was as if the rolling waves passed through the air and enlightened Su Shi. Was it the sound of the stream or his master’s words that flowed into his ears? I would suppose that his master’s teaching on insentient beings quietly echoed with the sound of the stream at night...