How does this passage develop the theme "Evil can never truly hide itself"?

In Dr. Jekyll and Mr. Hyde, the theme "evil can never truly hide itself" is the underlying theme that connects all the details together. For some time, the good attributes of the Jekyll/Hyde character were the only ones people around him see. He was able to hide his evil side in the darkness of the night. However, a secret that is so hideous cannot be forever hidden especially that it had consequences that affected the people around him. When his evil side was beginning to take more control of himself, he could not hide it anymore.