Simplicity: It means that things in the world are complicated and profound. Once human wisdom is realized, it can be transformed into problems that people can easily understand and deal with.
Change: it means that everything in the world is constantly changing and developing, and nothing is static. Without this change, everything in the universe would be difficult to form.
It's not easy: it means that under the premise that everything in the universe changes, only one thing remains unchanged, that is, what can transform everything into everything remains unchanged. Or the law of everything changes is the same.