What is the theme in Hamlet by William Shakespeare?

There are so many themes that you can consider.I like Hamlet's point about how life is transitory. Hamlet constantly muses about the transitory nature of life. We live and we die and our meaning will be lost in time. Hamlet obsesses about what it means to be alive and what it means to be dead. His existential angst is especially poignant near the end of the play when he seems to know his death is at hand. There's a special providence in the fall of a sparrow. If it be now, 'tis not to come. If it be not to come, it will be now. If it be not now.