I've found that when you come into conflicts with people, you go through so many emotions and most of them are negative. And as you try to work through them you realize that the only way to get out of your suffering is to forgive and forget. To some extent you convince yourself that you have done just that until you come into a similar situation, and you realize you're far from the wise words of forgive and forget. So to me this quote is way to gain a new perspective, so while you may come to similar conflicts, your way of looking at it changes and you move from suffering to serenity. Forgiveness will not change the past but it will enlarge your future.
Easier said than done right? Of course it is but rewards are so WORTH it!