It's Reciprocal
Proverbs 27:19 As in water face answereth to face, so the heart of man to man.
When we look into the mirror and reflect on our true nature as no one can do for us, then we are able to accurately assess our character and adjust the areas of our lives that need adjusting.
The result of this process yields a cleansing to our heart, or more accurately, our life passion. This, in turn, is reflective in our friendships, causing this very unique application:
Proverbs 27:17 Iron sharpeneth iron; so a man sharpeneth the countenance of his friend.
It’s reciprocal!
Go forth sharpening and be sharpened!