The Hamlet Project

I like that the “thou” in this sentence is implied. We know he means “thou” rather than “you” because “dost” and “you” do not go together. The “dost” without the “thou” adds an extra layer of familiarity and ease; It suggests to me that Hamlet has become pretty comfortable with Horatio. Most of us start to use a shorthand when we’re close to someone; We leave out unnecessary words. We shorten phrases and summarize references to inside jokes with single words. Hamlet doesn’t need to say “thou” when asking Horatio about his knowledge of Osric and he can also skip right to his own opinion of the man.
I don’t know a lot about waterflies but I suspect that at least one of their qualities that brings them to Hamlet’s mind on this occasion is the fly’s tendency to irritate. A fly, especially on the water, will buzz around and around. They will alight and land. They will not catch a single hint or even an instruction to go away. They will get too close to your eyes, your ears and sometimes cause a bit of chaos while trying to swat them away. But they are ultimately harmless.