Inna seidharai oruthhal avar naana nannayam seidhu vidal - Tirukkural
Avenge yourself on he who does ill to you by shaming him by doing good to him and forgetting both the evil he did and the good you did in return - Loose translation
One does try to see Tiru as still a worthy adviser in contemporary times but it is certainly an uphill task. I mean, yeah, even when someone advises you to turn the other cheek, you tend to ask what if he hits that one as well. Clearly, you think of even that as rank idiocy as advice. Except, of course, if the guy who is advising is actually keen on getting you thoroughly beaten up.
And Tiru goes way beyond even that. I mean, if someone slapped you, you not only have to keep from hitting the guy back but you also have to reward him for having slapped you. Let that impression of you get out and people will be queuing up to beat you.
And what was that thing about 'shaming' the guy? Really? Far as I can see, if someone hit me and I went out of my way to do good to him, all the chap would think was that he had frightened me so much that I was trying to please him. Far from feeling shamed, he would probably preen about it.
You know, perhaps Tiru did write it for different times. Yeah, the chap himself may not have felt shame even in Tiru's day but....see, it was probably a time when everyone knew everyone else in the neighborhood. So, the evil he did and the good you returned would all be visible to everyone around you, so he would be shamed in Society. And, yeah, if you went around harping on the evil and the good yourself, opinion would not favor you. So, it is best that you yourself totally forget both. Nowadays, when you hardly lift your head from your smartphone to even see where you are going, cannot identify three neighbors anywhere else to save your life...what society, what shame?
Tiru possibly thinks that all other people around us are not villains. That if someone hurts you, it is more likely a misconception than outright villainy that causes the hurt. So, yes, if you forget the hurt, help him when he is in need, he is likely to be ashamed of having given in to a misconception and hurt you, whereas, if you went on a rampage, it would most likely end up with him feeling vindicated and an enmity sealed for life. In any case, hugging the hurt of the evil someone did to you, periodically taking it out for inspection and burning yourself up with it...well, it is like opening the scab on a wound over and over again, never allowing it to heal and, possibly, causing an infection. So, of course, the chappie wants you to forget it.
Now, THAT is a crucial assumption. That people who cause hurt to you are not necessarily doing it because they take sadistic pleasure in hurting innocents but because they feel they have reason to do so. If that is true, then possibly doing as Tiru says could cause them to revise their opinions.
But...I mean, like, how could anyone feel any reason to want to hurt such a lovable person like me. Unless they are black villains. And be a sort of boy scout to these villainous people? How stupid do you think I am?