And Shem and Yefet took the garment, and placed
it on both of their shoulders. They walked backwards, and they covered their father's nakedness; their faces were turned backwards, and they did not see their father's nakedness.
The Baal Shem Tov taught: Flaws that you see in someone else are a reflection of your own imperfections. G-d leads us to notice these shortcomings in someone else, for our own deficiencies in that particular area would have
otherwise gone unnoticed.
This "chance discovery," says the Baal Shem Tov, is not only about helping your friend; there's something in it for you too, it brings attention to the areas in which you too could use critique and improvement.
The incident of Shem and Yefet protecting their father's honor alludes to this idea. The Torah relates that when Noach was drunk and lying naked in his tent, Shem and Yefet entered backward, so as not to see their father's nakedness, and they covered him. Now, the Torah states that Shem and Yefet faced backward, in which case they obviously couldn't see their father, who lay naked in front of them.
Nevertheless, the verse emphasizes that Shem and Yefet "did not see their father's nakedness." In other words, not only did they not see their father naked since they faced the opposite direction, they also did not "see" his nakedness and shame; all they saw was a situation that demanded their assistance.
-- From: Lightpoints