Is change a constant if it is always changing?
In writing we are using abstraction to communicate.
We read tree and think of a tree but our thought isn’t linked directly to the referent, to the exact tree the author is so concerned with (and, we’ll assume, has dealt with directly). We think up our bubble of associations with the sounds people make with their mouths, and in particular the sounds t-r-ee when said all at once, and go into our brains to remember what a t-r-ee is. Only the speaker has an experience with the tree that is written about. Even when the thing is named directly and we think we have a pretty clear idea of what the author is describing, the tree itself is lost to time and relegated to imagination.