"Take care of him. He bites."
When David arrives at Salem House, on orders from Mr. Creakle, Mr. Mell immediately attaches a sign to David's back: "Take care of him. He bites." (By the way, in this case, "Take care of him" definitely does not mean, "Be nice to him." It means, "Be careful around him.") At the level of the plot, this sign is a petty revenge from Mr. Murdstone, whose hand David bites when Mr. Murdstone whips him. But symbolically, this sign demonstrates the intense isolation that David feels once he has been slowly squeezed out of his mother's life and, eventually, out of her home. He has been labeled a bad boy by Mr. Murdstone – unjustly, certainly – and he is powerless to challenge Mr. Murdstone's orders.
The sign is so humiliating to David that he lives in fear of when the other boys will arrive at school for the start of the new term: he doesn't want them to start mocking him or avoiding him for this sign that he is different. After all, every first day of school is awful – how much worse would it be to introduce yourself to a new school with a sign on your back saying you bite? The sign underlines David's embarrassment and shyness at his change of circumstances.
In yet another moment of foreshadowing, David finds a true friend in Traddles: Traddles is the first boy who sees the sign. And instead of teasing David or making his life a misery, Traddles treats the sign as a game. And David is hugely relieved. David also hears from Steerforth that his sign is, "a jolly shame" (6.30) – in other words, that the sign sucks – and so David is doubly comforted. After he has been accepted by his peers, the sign quietly disappears. Oh, there's a nasty reason for its vanishing, since Mr. Creakle takes the sign off so that he can beat David's back more easily. But symbolically, the sign goes away because David has made himself a place in the society of Salem House. He's no longer as isolated as he once was, with Traddles and Steerforth at his back.
Dickens occasionally throws in a few criticisms of people like Julia Mills and the Waterbrooks, society types who think a lot about money and reputation and not very much about other people. But there is no greater symbolic showdown between the power of money and the power of personal feeling than in the cases of Mr. Micawber and Mr. Peggotty.
Both Mr. Micawber and Mr. Peggotty face this interesting crossroads where they are offered money in exchange for something of emotional or moral value. In Mr. Micawber's case, Uriah Heep assumes that Mr. Micawber will keep quiet about his plots against the Wickfields and David because Uriah Heep is paying Mr. Micawber a lot of money.
In Mr. Peggotty's case, Mrs. Steerforth explicitly offers him cash as a payoff because her son has abducted Mr. Peggotty's adopted daughter, Emily. And Mr. Peggotty also receives a couple of cash payments from Emily herself while she is on the road, as an apology for running away.
In both of these cases, Uriah Heep and Mrs. Steerforth are offering blood money – cash in exchange for letting the status quo stand. And both Mr. Micawber and Mr. Peggotty refuse: Mr. Micawber collects evidence to expose Uriah Heep to David, Miss Betsey, and Traddles. And Mr. Peggotty rejects Mrs. Steerforth's offer point blank and then holds onto little Emily's payments until she is found so that they can be returned to the Steerforth family.
These occasions both demonstrate in a nutshell the text's lesson about money: you can never allow it to dominate your moral choices. And the assumption that poor people will be ruled by money makes you look really bad.
Mr. Dick's Memorial
We get into this in detail in Mr. Dick's "Character Analysis," but we do want to mention here that Mr. Dick's Memorial is, indeed, a symbol. We haven't forgotten about it! We've just discussed it elsewhere.
The Crocodile Book
In one of David's first memories, he recalls reading to Peggotty from a book about crocodiles. In the middle of this fascinating subject, David suddenly turns the discussion to marriage, asking if Peggotty ever plans to get married. Peggotty, who is an adult and realizes what Mr. Murdstone's presence in David's mother's life really means for David, starts looking very odd. Peggotty wonders why David is suddenly worrying about marriage. Peggotty decides to change the subject, turning David back to his crocodiles.
Just before Mrs. Copperfield marries Mr. Murdstone, David is sitting with his crocodile book when Peggotty asks if David wants to go on his first trip to Yarmouth. David's happy early memories of being taught to read at home involve the crocodile book. When David comes home for the holidays before his mother passes away, he remembers reading to Peggotty from the crocodile book, "in remembrance of old times" (8.96). When David is grown up and he goes to visit Peggotty in Yarmouth, he finds the crocodile book sitting on a table for him. And finally, in the last chapter, as David surveys his happy family, he sees Peggotty reading to David's own children from the crocodile book.
In other words, David's crocodile book, his first real book, symbolizes all the warmth and security that Peggotty brought to his early childhood. It also represents her unchanging personal loyalty to David over the years, until she is now trusted with looking after David's kids. The crocodile book is like the opposite of the "Take care of him. He bites" sign: it represents closeness to other people and family contentment.