It is both natural and necessary. Mourning is nature's way of healing us when we've been separated from someone we love. Within this mourning we react to our loss with a multitude of responses. Our grief wears many faces. If we've grieved before, we recognize it immediately.
Some people describe it as sadness, but it goes well beyond sadness.
It jolts our physical, mental and emotional being. It touches us down to our very soul. Grief causes us to think, feel and behave differently than we would ordinarily. We simply do what has to be done, caring little how or why. The numbness of that shock , which may last hours or weeks, serves an important purpose.