What does Bodhi as a Mirror mean?

This sentence should come from the son of the master: the body is a bodhi tree and the heart is a mirror. Always clean up, don't get dust!

In this song, the body is compared to a bodhi tree. And the heart is like a mirror. Wipe it often, don't let it get dusty!

After seeing this poem, Master Liu Zu wrote a famous poem: Bodhi has no trees, and a mirror cannot stand. Nothing, so where did it cause the dust?

The realm of this song is the realm of an enlightened person. Bodhi is invisible, and so is the heart. Originally, all the laws were illusions, and nothing was true. Why not make dust?