Experience, they say, is the best teacher..Although, I believe knowledge is. But the experience is gotten from the past. And they are meant not just to teach us a lesson but others around us too. Now, holding onto the (bad) happening in the past would make us not learn and grow. Even, medically, holding grudge against somebody or a happening secretes some bad substances into our body. One would not feel free when you hold a grudge and do not forgive..we may not forget. But if you forgive yourself and maybe another person, you'd feel free..it'd be like a burden was lifted from your whole body - I am talking from experience. @samminator