三件事最坚苦∶守旧奥秘，忘怀危险驯良用精神。

The three things most difficult are, to keep a secret, to forget an injury, and to make good use of Labour.

youdao

三件事最坚苦∶守旧奥秘，忘怀危险驯良用精神。

The three things most difficult are, to keep a secret, to forget an injury, and to make good use of Labour.

youdao