Generally speaking, a gentleman will know how to avoid the edge for a while and will not be arrogant because of his talent. A gentleman is knowledgeable and active in thinking, but usually he doesn't show his talent for the overall situation. For people with virtue and insight, the richness of emotions also exists, but such people know how to restrain the expression of external emotions, so that they can consider themselves and take care of the overall situation. Generally speaking, a gentleman will not be arrogant because of his talent, nor will he show emotions on his external expression.
To sum up, the meaning of this sentence is: generally speaking, gentlemen are talents who are not exposed, and they will not reveal their emotional changes to the outside world.
Extended data:
There is an old saying that "a tree in the forest is beautiful, and the wind will destroy it". Even people who read widely often need to show it at critical times. If wisdom is not displayed in a reasonable place, it is easy to be jealous and bring trouble. There are always some people who are smarter than they are, and they are all thumbs in dealing with people. They try their best to show their personal skills and highlight their talents and wisdom.
The same is true of emotional changes. Don't show your inner thoughts on your face. If your mood changes are too straightforward, you may hurt others and bring trouble to yourself.