The main theme here is: being loyal to one's country may mean being disloyal to an individual.
Brutus was loyal to Caesar but he was more loyal to Rome.
The next soliloquy Hamlet has after seeing the ghost of his father is in Act II, Scene ii after the players, Rosencrantz and Guildenstern, have left him alone. In this soliloquy ("what a rogue and peasant slave am I"), Hamlet expresses his frustration with the fact that the actor could create tears in an instant about a fictional character, but he has lost his actual father and cannot even do anything about it. Through this he also decides on the plan to try and catch Claudius' guilt.
The area of California in which we live is dry and arid, and yet we see grass growing in large areas around homes and office buildings. This practice is not only wasting water but is costing the city too much money—money that could be used for other projects.