There is more. By saying what he did, Joseph was also admitting that, if he had been in their shoes, he would have done what they did. He did not condemn them for what they did. He had reached an understanding of their actions. For the one who totally forgives from the heart, there is little self-righteousness. Two reasons we are able to forgive are: We see what we ourselves have been forgiven of. We see what we are capable of.
