How do the four ghosts contribute to the changes in Scrooge's attitudes towards the poor and Christmas?

The four ghosts expose Scrooge to his past, present, and future. Marley, Scrooge's business partner describes the burdens he carries after death, warning him. The Ghost of Christmas Past takes Scrooge back to his childhood and reminds him he was once capable of love, ready to marry, and employed by a generous man, who looked out for his employees. The Ghost of Christmas Present showed him his life, his lack of empathy, and even his greed. The third ghost showed him the future that could be..... a future that could change if Scrooge himself was willing to change.