The thief was finally caught, not by the police, but by his own conscience, which led him to confess.

conscience 由前缀 con-（表示"共同"）和词根 science（知识）组成，字面意思是"共同知晓"。这个词指人内心辨别是非的道德意识，即"良心"。当一个人做错事时，conscience 会让他感到内疚不安。