In Dickens' David Copperfield, the character Uriah Heep refers to David sometimes as "Mister Copperfield" and sometimes as "Master Copperfield." Other times, he makes a point to say something like
'Oh, really, Master Copperfield,' he rejoined—'I beg your pardon, Mister Copperfield'... (emphasis mine)
As can be expected with Dickens, Heep works this mister/master business into almost every chapter he appears in. What is its significance? Please, are you able to explain without any massive spoilers to someone only two-thirds of the way through? So assume in answering that I have a good general impression of Heep's character but don't know anything that may occur after Chapter 40 or so.