Good medicine tastes bitter and is good for illness, but advice when most unpleasant is good for action.

"Good medicine tastes bitter and is good for illness, but advice when most unpleasant is good for action" means accepting others' opinions and criticisms with an open mind, or educating people to be brave in accepting criticism. Good medicine is mostly bitter, but it is beneficial to cure diseases; Most of the languages that teach people to be kind are not very nice, but they are helpful to correct their shortcomings.

"Good medicine tastes bitter and is good for illness, but advice when most unpleasant is good for action" comes from Historical Records. Pei Gong Liu Bang100,000 rebel troops broke through the customs, defeated the Qin Guan garrison in Lantian, dominated the world and successfully entered Xianyang. After Liu Bang entered Xianyang Palace in Qin Dynasty, he was attracted by the beauty and treasures in the palace, and got carried away, so he was ready to stay in Qin Gong and have a good time. His brother-in-law Fan Kuai advised him, but he wouldn't listen. At this time, Sean went into the palace to directly remonstrate, severely reprimanded Liu Bang, explained his mistake in doing so, and said, "Advice when most is unpleasant is good for action, and poison is bitter for illness. Please listen to Fan Kuai." Pei Gong reluctantly left Qin Gong and announced that the army would leave the city and be stationed on the bully on the outskirts of Xianyang, so as not to disturb the people.

This sage is to educate people to be brave in accepting criticism, which is often used to explain that we should treat others' opinions and criticisms correctly.