What is the purpose of Scene IV?

This scene illustrates Capulet's complete control over his family and Juliet's destiny. Capulet changes Juliet's wedding date partly because he believes it will assuage her sadness, Lord Capulet decides right then that Juliet will marry Paris, and that the wedding will take place later that week. He comments, "I think she will be ruled / In all respects by me" (3.4.13-14). He orders Lady Capulet to inform Juliet about the matter, and then leaves for bed.