This is from Rembrandt's "The Prodigal Son". The goal here was not to draw the whole picture but just the areas that you want the viewer to look at. When you look at Rembrandt's painting your eye immediately goes to the father's face first. This is done through contrast. There is the greatest amount of contrast around the father's face so your eye is lead there. Then it goes to the son's feet, the father's hands and then to the older brother. Each area has to have less contrast then the next. So if you want to have the feet stand out second, you make it have less contrast than the father's face, but more than the father's hands.
The reason behind creating focal points is so that you can tell a story. What message are you trying to get across? What feelings do you want the viewer to experience? Rembrandt wanted you to experience the father's love for his son that turned away from him. You see his face looking at his son. Then you see the son's feet and that his shoes are falling apart, he has nothing. Then you look at the hands of the father. One of the father's hands is gentle and the other is pulling the son toward him. The older brother has crossed arms and a stick as if standing back in judgement.
