Why does the author refer to a tree as unchanging?

He is using figurative language. when you look at trees, young or old, it looks like they never move. they just sit there. and the old trees look like they were there forever. such as a poem I read named Evangeline. in the poem, the author describes the oak trees an "Druids of old." Druids were a very old order of priests.

Means how the story stays the same