The sentence "Do what you know you can't do, and do what you don't do" is actually quite easy to understand if you take it literally. In fact, the word "gentleman" was added before the original sentence. Although it meant men and gentlemen at that time, it can refer to all people now.

we know that some things can't be done, but we have to do them. Some things can be done, but we can't. For example, anyone can do something to steal the chicken and steal the dog, but it is something that cannot be done. A gentleman or a gentleman must distinguish between what can be done and what can't be done.

and when we do something, we should be flexible. If we do it, we do it, and if we don't, we don't do it. Whether he is right or wrong, he must be responsible for what he has done.

when we do things, we should be able to distinguish right from wrong and follow our own heart. We can't do things that commit crimes, and we can't do things that harm others and do nothing for ourselves. This requires that you can follow your heart as a modest gentleman.

and when you do things, you should also judge the situation and follow the trend, and never go against the sky. Although some people are called heroes for doing things that others dare not do, some heroes also pay a huge price.

To do what others dare not do is to set a precedent. As an old saying goes, you should eat shit first. This means that when we do something, we must be the one who eats the first candy.

In fact, this sentence points a bright way for our life. When we are confused and don't know what to do, it is a good choice to read this sentence.