David Copperfield: Metaphor Analysis

Devils and angels
The novel has a clear-cut moral structure, whereby the good characters are clearly distinguishable from the bad characters and on the whole, good things happen to good people and bad things happen to bad people.
This dividing line between good and evil is reflected in the imagery used to describe certain characters. Uriah Heep's physical appearance and nature are described in demonic imagery. He writhes like a snake, the Biblical symbol of the devil, and in Chapter XLIX, Mr. Micawber refers to him as a "serpent." He has red hair and eyes, the latter being characteristic of portrayals of the devil. He is seen as barely human: in Ch LII, Mr. Micawber calls Uriah a "monster in the garb of a man."
Like the devil, Uriah gains power over people; it could be said that he possesses them. In Chapter XXVI, when Uriah and Agnes are traveling on same coach, she is shown inside, whereas he is on the roof, serpent-like and devilish. He is described as "her evil genius writhing on the roof, as if he had her in his clutches and triumphed." In line with Uriah's parasitic behavior, there is the suggestion that he is a kind of vampire when, in Chapter XXV, David feels the impulse to seize a red-hot poker from fire and run Uriah through with it; it will be remembered that the time-honored way of killing a vampire was to drive a stake through its heart.
The imagery of evil surrounding Uriah extends to his mother. In Chapter XXXIX, Mrs Heep fixes the "evil eye" on David and Agnes; David imgaines that her knitting is a net to entrap them.
Littimer too has his share of demonic imagery, as befits a character whose outward appearance is deceptively "respectable" but whose soul is corrupt. In Chapter LI, Mr. Peggotty refers to Littimer as a "spotted snake."
Reinforcing Dickens's strong distinction between good and evil characters are references to good and bad angels. In Chapter XXV, Agnes warns David that Steerforth is his "bad angel," whereas David thinks of Agnes as his "good angel" In Chapter LI, Mr. Peggotty calls the woman who rescues Little Em'ly after she escapes from Littimer an "angel."In Chapter LII, Uriah watching Agnes is likened to "an ugly and rebellious genie watching a good spirit." David repeatedly associates Agnes with a stained glass window in a church, (for example, in Chapter LIV) suggesting sainthood or divinity.
Predatory animals
Images of predatory animals are used to convey cruelty, destructiveness, opportunism, and exploitation of other people. In Chapter XXVI, Uriah is described as being "like a great vulture: gorging himself on every syllable that I said to Agnes, or Agnes said to me." In similar vein, in Chapter XXXIX, Uriah and his mother are "like two great bats hanging over the whole house." In Chapter XLVIII, David gives up trying to improve Dora's mind, fearing that if he continues, he will "degenerate into the spider again, and be for ever lying in wait." There is an implicit reference to Mr. Murdstone, who acted in just such a predatory and cruel way with David's mother.
Symbols
Mr Dick's kite
Mr. Dick loves to fly his kite. The kite's element is air, and its flight symbolizes Mr. Dick's detachment from worldly matters and mundane society. It also suggests the instinctively spiritual and angelic aspects of his nature.
Rosa Dartle's scar
Rosa's scar is an outward symbol of a deep inner wound that she keeps concealed. The scar (and, it is suggested symbolically, the inner wound) was inflicted by Steerforth in a moment of exasperation. Rosa loves Steerforth, but is unable to express her love freely, whether because of his indifference or her fear of rejection, or both. She has become bitter and twisted, obscuring her true meaning in sarcastic and elliptical speech. However, the scar becomes livid in moments of high emotion, which always involve Steerforth. Thus the scar is the most honest aspect of Rosa, in that it says what she cannot.
The sea
The sea in this novel both gives life (Mr. Peggotty and Ham are fishermen) and takes it away (the people in Mr. Peggotty's household have been widowed or orphaned by the sea). It represents a force of nature that is beyond the control of man and beyond superficial and egotistical qualities like vanity. In swallowing Steerforth, it both shows up the trivial nature of Steerforth's character, and acts as a force of fate in destroying the destroyer.
Mr. Peggotty is the character who is most in tune with the sea, in that he respects its power, and he is also in tune with the rhythms of life and death. He knows that Mr. Barkis will die with the ebbing tide, and is proven correct. This shows that Mr. Peggotty is a person of simple, uncomplicated virtues, in contrast with the sophisticated wiles of people like Steerforth and Uriah.