Hello. You have not informed which story this question refers to, which makes it difficult to answer your question with specific evidence from the text, but I will try to help you in the best possible way.
The moral shown in the question above shows that being honest with who we are is the best way to position yourself in any situation, even if that honesty shows your worst side. That's because it is not correct to lie about who you are, hiding defects that are part of you. The correct thing is to assume your defects and work to change them, making them the best elements of your personality.
If the minister spoke this argument, it is because he went through an experience where being honest was positive, it was better than hiding his negative points, which indicates that it is possible to learn this lesson from the minister's experience.
It is likely that it has several lessons in this story, mainly regarding the positivity of being true always.