Tzitzit, a reminder of divine justice

“And you shall see them and remember” (ibid.), and it is written “Remember what Amalek did to you” (Deut 25:17). What is the reason for this? Rather, it may be compared to a son, who broke through the fence and was bitten by a dog. Whenever the father wishes to rebuke his son, he says to him: Remember how the dog bit you! Here too, “you shall see them and remember,” for that is the place where souls go to be judged. Likewise, “and whoever was bitten and saw it, and lived” (Num 21:8). Why? Rather, when he is taken for affliction, and sees the image of that which bit him, he is fearful and prays before God, and he knows that this is his punishment because of his guilt. 

So long as the son sees the whip of his father, he is afraid of his father. Once he is saved from the whip, he is saved from everything. What caused him to be saved? That in his suffering he saw the whip. That whip caused him to be saved. And for this it is written, “and saw it, and lived.” He saw the whip with which he was beaten, and it was his salvation. Here too, “and you shall see it, and remember… and do.” Certainly! For that whip causes him to return to His service constantly.

http://hitzeiyehonatan.blogspot.ca/2009/06/shelah-lekha-zohar.html