He keeps turning things over in his mind.
I've come across with the phrase above in a novel.
I don't understand the meaning. I wonder which one is the phrasal verb?
Could you please explain it to me?
The full text:
James reels with shock and grief. He keeps turning things over in his mind. He remembers how a couple of years ago Bradley had begun dealing drugs. He thought he’d seen an opportunity to make some easy money, but it hadn’t turned out the way he’d expected. Suddenly, James shakes off his apathy, and springing up out of his chair, cries, “Who did this? Which of you killed my son?” He feels an overwhelming grief and rage. “Why? Why in God’s name would anyone kill my son?” His voice is wild, accusing, as he looks at each of them in turn. He can see that he has frightened them.