You understand me: I'm a beast, I know. But see, now—why, I see as certainly As that the morning-star's about to shine, What will hap some day. We've a youngster here Comes to our convent, studies what I do, Slouches and stares and lets no atom drop: His name is Guidi—he'll not mind the monks—They call him Hulking Tom, he lets them talk— He picks my practice up—he'll paint apace. I hope so—though I never live so long, I know what's sure to follow. You be judge!
Bro Lippo doesn't seem to have a very high opinion of himself, does he? He calls himself a "beast." But wait—this is a way for him to make a temporary alliance with the guard by pointing out that they have common ground.
There's a kid, Lippo tells the guard, now at the monastery who is also studying painting. His name is Guidi, a.k.a. "Hulking Tom." This kid must be pretty big, if he's hulk-like. Let's just hope he doesn't have an anger problem, or if he does that his robes are expandable.
Anyway, this Guidi is quickly picking up Lippo's mad painting skills. And Lippo knows what's going to happen, the guardsman will eventually see.
This probably just means that Lippo expects Hulking Tom to get into the same hot water.