Grief is something that is difficult to describe. It's different in each individual circumstance and it varies by each individual as well.
I remember being a young girl in college having broken up with my fiance. I remember that it felt like the end of the world. I truly was grieved over my circumstance. I sought the Lord continuously, and the His Word was the only thing that brought me joy. I wept many tears.
Fast-forward ten years, I was married, had a 3 year old, and gave birth to a new son for whom we had prayed. We had prayed for him to make it when we were fearful something was wrong. We prayed for him to be normal when we feared he was not. We prayed that the doctors were wrong. We had faith that all would be okay. He was born, and he wasn't okay, but he lived. There was a different grief then. At the time, I didn't see it at as grief, or I would not have called it that for fear of hurting those who have actually lost loved ones.
Today, I can call it grief. I see that it is the grief of disappointment over what we expected. Yes, we have our son, and he is wonderful in his own way, but before we saw anything hopeful, there was grief. The night of grief is not passed. Although we often have glimpses of the morning.
Our joy comes in the mourning that we experience; for if we never experienced that night, we would never see the brightness of the dawn.
This verse as a whole uses opposites to emphasize a truth. The truth is that when we have known the worst - the opposite seems all the more beautiful.
I had known a child who learned to play with toys and suddenly stopped playing, and now the joy of seeing him begin to play again is indescribably. The sorrow we experience when someone is disappointed in us is overwhelmed by the joy we experience at restitution. God does this in our grief. He gives us mourning, but He also brings the morning.