"The buddha way does not appropriate the voice of sentient beings and apply it to the voice of insentient beings. Insentient beings do not necessarily speak dharma with a voice heard by the ears. Similarly, sentient beings do not speak dharma with a voice hear by the ears. Now ask yourself, ask others, and inquire, 'What are sentient beings? What are insentient beings?'
In this way, concentrate and study what insentient beings always speak dharma is. Foolish people may think that the sound of trees, or the opening and falling of leaves, is insentient beings speaking dharma. Such people are not studying buddha dharma. If it were so, who would know and hear insentient beings speaking dharma? Reflect now: are there grass, trees, and forests in the world of insentient beings? Is the world of insentient beings mixed with the world of sentient beings? Furthermore, to regard grass and trees as insentient beings is not thoroughgoing. To regard insentient beings as grass, tress, tiles and pebbles is not enough". 'Insentient Beings Speak Dharma', 'Mujo Seppo'.