N'chash HaN'choshes is the joke of jokes. It is an example of true Gam Zu L’tovah, which has the power to change extreme evil to extreme good. And you take the Nachash, which symbolizes the evil Lashon Hara that Yidden spoke, and you put it high up, to show that: B’makom sheba’alei teshuva omdim ein tzaddikim g’murim yecholin la’amod. Baalei Teshuva are even GREATER than pure Tzaddikim! By doing Teshuva, their “sin” (symbolized by the Nachash) is way up high, and causing Yeshuos Gedolos.
This is the way we have to look at all our misfortunes, and sins, and Ne'filos in life; they are potential greatness, which end up high on a banner and causing supernatural goodness for everybody. Your “Nachash” (sin) becomes the biggest Mitzva and it becomes your best friend. I heard from a Mekubal, R' Yitzchok Cohen Zatzal, that by doing Teshuva, the evil Malach you created with your sin (whose job was to hurt you) becomes your best friend who defends you.
Height symbolizes greatness, and the Avos were called mountains, and the Torah was given on a mountain. When you sin, you should realize it is a yerida l’tzorech aliya: a step down which is just a stepping stone for even more greatness, and soon (instead of becoming low) you are becoming top-top and bigger than Tzaddikim G'murim. Look at that ugly sin (snake) sitting all the way on top!
