Not to do any evil, to cultivate good, to purify one's mind, this is the Teaching of the Buddhas. 諸惡莫作，眾善奉行；自淨其意，是諸佛教
When we look at the face in the mirror, we can understand to a certain extent the nature of the mind. The face is the mirror for us to see the reflection of the mind.
Venerable K. Sri Dhammanada