Act 3, Sc. 2, lines 135-140: What is the function of this dumb show in Hamlet's plan?

[Enter Prologue]

Hamlet. We shall know by this fellow. The players cannot

keep counsel: they'll tell all.

Ophelia. Will he tell us what this show meant?

Hamlet. Ay, or any show that will show him. Be not you

ashamed to show, he'll not shame to tell you what it means.

Ophelia. You are naught, you are naught. I'll mark the play.

Prologue. For us and for our tragedy,

Here stooping to your clemency,

We beg your hearing patiently. [Exit]