I particularly like this:
Most people tend to use the words grief and mourning interchangeably. However, there is an important distinction between them. We have learned that people move toward healing not by just grieving, but through mourning. Simply stated, grief is the internal thoughts and feelings we experience when someone we love dies. Mourning, on the other hand, is taking the internal experience of grief and expressing it outside ourselves....attempting to mask or move away from grief results in internal anxiety and confusion. With little, if any, social recognition of the normal pain of grief, people begin to think their thoughts and feelings are abnormal. "I think I'm going crazy," they often tell me. They're not crazy, just grieving. And in order to heal they must move toward their grief through continued mourning, not away from it through repression and denial.