Forgiveness is the key to action and freedom. Without forgiveness life is governed by an endless cycle of resentment and retaliation. When someone says 'I can forgive but I cannot forget', is only one way of saying, "I will not forgive." Forgiveness ought to be like a cancelled note, torn into two, and burned up, so that it never can be shown against one.
The weak can never forgive -- forgiveness is the attribute of the strong.