The Master [Confucius] said, “When you meet someone better than yourself, turn your thoughts to becoming his equal. When you meet someone not as good as you are, look within and examine your own self.”
Confucius: the First Ten Books; trans D C Lau. Penguin, 1979 4:17
In its essence this is the principle that one can’t judge others without first judging oneself; or, to be more specific, be careful of detecting ‘faults’ in someone else while ignoring those same negatives in yourself. The good news, it seems to me, is that this principle is obviously highly useful to oneself; the other side of the coin, as it were. When I see how another person handles a negative characteristic of theirs, such as self-pity, the experience usually shows me clearly how to correct or modify the same fault in myself. “So that’s how I come across to people!” It’s the basis of the Golden Rule.