江山易改，本性难移 Mountains and rivers are easy to change, but human nature is difficult to change.
Explanation
比喻江河易于改道，而人的本性却很难改变。
Metaphor: Rivers are easier to redirect, but human nature is hard to change.
Origin Story
从前，有个叫张三的人，他从小就贪玩，不爱学习。父母多次劝说，老师也多次教育，可他就是改不了。后来，他长大了，成了一个地痞流氓。尽管他多次进监狱，但出来后依然故态复萌。人们都说他江山易改，本性难移。其实，人的本性是可以改变的，只要有足够的毅力和决心，坚持不懈地努力，就能克服自身的缺点，改掉坏习惯。张三的故事告诉我们，一个人能否改过自新，关键在于自己是否下定决心，以及是否付出行动。
Once upon a time, there was a man named Zhang San, who was playful and didn't like to study since he was a child. His parents persuaded him many times, and his teachers also educated him many times, but he just couldn't change. Later, he grew up and became a hooligan. Although he went to jail many times, he still relapsed after being released. People said that it was difficult to change his nature. In fact, human nature can be changed, as long as there is enough perseverance and determination, and unremitting efforts, one can overcome one's shortcomings and change bad habits. The story of Zhang San tells us that whether a person can reform himself depends on whether he is determined and whether he takes action.
Usage
用来形容人的本性很难改变。
Used to describe that human nature is difficult to change.
Examples
-
他表面上很友善，其实内心狡诈，真是江山易改，本性难移。
tābiǎomiànshànghěn yǒushàn, qíshí nèixīn jiǎozhà, zhēnshi jiāngshān yì gǎi, běnxìng nán yí.
He is very friendly on the surface, but his heart is cunning. It is really difficult to change a person's nature.
-
小偷屡教不改，真是江山易改，本性难移。
xiǎotōu lǚ jiàobù gǎi, zhēnshi jiāngshān yì gǎi, běnxìng nán yí
The thief has not changed despite repeated warnings. It's really hard to change a person's nature.