What are the motifs in The Ox-Bow Incident by Walter Van Tilburg Clark?

Mob mentality is a recurring idea in the story. It is said that when a large group of people gather together, the opinions of one tends to spread to all of the others. In this novel, the author presents a mob that becomes convinced of the need to hang a group of men for the murder of a man these people are not even sure is dead. As more people gather and hear Farnley talk about the need for justice against these killers, the more people become convinced that hanging the guilty men is necessary.