Doctors, like priests, need to take oaths. Patients undress in front of you and tell you inner secrets that they wouldn't communicate to anyone else because you are a doctor.
醫師和牧師一樣都需要宣誓，病人在醫師面前寬衣解帶、把內心心事說出來，他不會跟別人講，因為你是醫師。