In the following speech, Claudius seemingly comforts Hamlet by saying that we all share the "common theme" which is the "death of fathers." In his line of argument, excessive mourning is vulgar and unnatural because everybody is to go through the death of the beloved at one time or another. In reality, Claudius seeks to manipulate Hamlet by dispersing his gloomy thoughts and desire to rebel against the new king.
Yet, Claudius in spite of himself reveals an ironic truth that the underlying theme of this play is the filial duty of a son to honor his dead father. There are three young men and a young woman in similar circumstances who have to contend with the death of their fathers: Hamlet, Fortinbras, Laertes, and Ophelia. These literary foils provide a contrast that helps illustrate Hamlet's struggles and agony.