My father used to say, (1)
We're at the poem's first line, and the speaker already turns it over to her father. We are introduced to the speaker's father before we learn anything about her. Does that bother us? Maybe not. Usually when people begin a conversation with "My father used to say…," they are either going to tell us about how their father nagged them all the time, or they are going to tell us about how crazy and funny their father is. We love to complain about parents, and we really love how weird and out of touch they can be, right? On rare occasions, parents actually say something wise, and that's useful to hear too.
the mouse's limp tail hanging like a shoelace from its mouth – (7)
You know how parents like to say, "Don't talk with your mouth full"? Well, sometimes you can't talk with your mouth full – because that darn mouse is taking up too much room. We knew from the title that the poem would deal with silence, but we didn't expect this to be one cause for it. Notice how this line is much longer than the previous lines, as if it actually enacts how a mouse's tail dangles out of a cat's mouth.
and can be robbed of speech,by speech which has delighted them. (9-10)
The silence described here depends on someone having spoken. Speech (delightful speech) robs speech from superior people. One nice thing about these superior people is that they're not into one-upmanship. They're happy just to appreciate something great someone else said; they don't need to prove that they're the funniest or cleverest person in the room. By the way, is that what's going on here? Is the father's "delightful speech" robbing our speaker of her speech?