Soul of wit

In a conversation comparing the wordplay, linguistic innovation, and quotability of Joss Whedon (Buffy the Vampire Slayer, Firefly, Serenity, Much Ado About Nothing) and William Shakespeare (Macbeth, Hamlet, Much Ado About Nothing):

M: "...Of course, Whedon's soliloquies do tend to be shorter."

J: "Well, you know what they say about brevity..."

M: "'The soul of wit', yeah?

J: "Ooh, I like that! It's catchy."