See what Zhou Dunyi says.

In ancient times, a gentleman was a person with noble personality and good moral conduct.

Zhou Dunyi has already told us the truth in Ailian: Lotus is muddy but not dirty, clear but not evil. Thought out of the mire, but not contaminated, just like the author himself, in the dark officialdom, but not in cahoots, still maintained his noble character. Such people are gentlemen.

The ancients used the hollowness of bamboo to compare people's modesty, the cold resistance of bamboo to compare people's tenacity, and the greatness of bamboo to compare people's ambition. These are the image characteristics of a gentleman in people's minds.