Sadness, the Healer Emotion: Understanding and Transforming Grief

Why do we feel sad? Why does it hurt, and people suffer with grief and depression? How can we heal and transform sadness? And can it have a constructive role in our lives?
Why do we feel sad? Why does it hurt, and people suffer with grief and depression? How can we heal and transform sadness? And can it have a constructive role in our lives?