The central theme is the conflict between personal beliefs and professional ethics. The barber hates the captain for his actions, but as a barber, he has an obligation to serve his customers without harming them. This internal struggle over whether to take advantage of a dangerous situation for a political cause or to stay true to his profession is what the story is all about.
The main theme of 'Just Lather, That's All' is self - control. The barber is faced with a situation where he could take revenge on a person he dislikes. But he restrains himself. This shows that the story is about the power of self - control and how one should not let emotions overtake their actions, especially when it comes to ethical and professional responsibilities.