When Lockwood visits Wuthering Heights for the first time, the novel uses melancholy, Gothic imagery to indicate that the neighboring house is a forlorn, isolated, tempestuous place. Lockwood's visit also foreshadows the whole history of the place that Nelly will tell Lockwood about over the course of the novel.
Wuthering Heights is the name of Mr Heathcliff’s dwelling, ‘Wuthering’ being a significant provincial adjective, descriptive of the atmospheric tumult to which its station is exposed in stormy weather. Pure, bracing ventilation they must have up there, at all times, indeed: one may guess the power of the north wind, blowing over the edge, by the excessive slant of a few, stunted firs at the end of the house; and by a range of gaunt thorns all stretching their limbs one way, as if craving alms of the sun.
The house's very name, "Wuthering Heights," is derived from the strong winds that buffet the place, hinting that it's not only subject to literal storms, but also figurative ones. By describing the thorn trees with their stretching limbs as "craving alms of the sun," the novel personifies the trees as beggars and the sun as a benefactor; this simile also suggests that the residents of Wuthering Heights rarely experience goodness (light) and long for it.
The house's exterior is also marked by Gothic imagery:
Before passing the threshold, I paused to admire a quantity of grotesque carving lavished over the front, and especially about the principal door, above which, among a wilderness of crumbling griffins, and shameless little boys, I detected the date ‘1500,’ and the name ‘Hareton Earnshaw.’
Gargoyles are characteristic of spooky old buildings in Gothic literature. Also, the name and date carved above the front door foreshadow the 300-year Earnshaw family history that Lockwood isn't yet acquainted with, which will propel much of the novel's drama. At this point, all he (and readers) know for sure is that Wuthering Heights is very old, mysterious, and forbidding.
When Lockwood spends the night at Wuthering Heights, he dreams about Catherine's ghost trying to get in the window by his bed. At first, he thinks he hears a branch tapping on the window, but when he investigates, he finds himself clutching a ghostly hand. Morbid, terrifying imagery sets the tone for the tragic story to come:
[...] stretching an arm out to seize the importunate branch: instead of which, my fingers closed on the fingers of a little, ice-cold hand! The intense horror of nightmare came over me; I tried to draw back my arm, but, the hand clung to it, and a most melancholy voice sobbed, ‘Let me in—let me in!’ [...] ‘I’m come home, I’d lost my way on the moor!’
Up to this point, Lockwood has found his Wuthering Heights neighbors off-putting and strange, but with this dream, the novel takes a stark turn toward the downright frightening. The "icy" hand and weeping, "most melancholy" voice shock Lockwood, and readers, into realizing that Wuthering Heights has an even darker history than the house's Gothic architecture would suggest.
Soon after, when Lockwood asks, the voice identifies itself as Catherine Linton, not Earnshaw, even though Lockwood recalls having read "Earnshaw" etched into the bedside ledge many more times than "Linton." Lockwood doesn't yet know who Catherine is, much less that she married a Linton, which makes the ghost's existence seem more plausible, not a mere dream. Again, the dream foreshadows the whole history of Wuthering Heights that the household servant Nelly will eventually tell Lockwood.
The dream gets even more horrifying from here:
Terror made me cruel; and, finding it useless to attempt shaking the creature off, I pulled its wrist on to the broken pane, and rubbed it to and fro till the blood ran down and soaked the bed-clothes: still it wailed, ‘Let me in!’ and maintained its tenacious [grip], almost maddening me with fear.
Again, the shocking imagery of bloodied wrists and an unnaturally strong grip signals that the story of Catherine, Heathcliff, and Wuthering Heights will involve death in some way. The ghost's grief and persistence also suggest that Catherine Linton's story is still unresolved.
When Isabella believes that she has fallen in love with Heathcliff, Catherine and Nelly try to warn Isabella about Heathcliff's true nature, but she doesn't heed them. Catherine uses nature imagery to convey that Isabella would be completely at Heathcliff's mercy.
"Tell her what Heathcliff is—an unreclaimed creature, without refinement—without cultivation; an arid wilderness of furze and whinstone. I'd as soon put that little canary into the park on a winter's day as recommend you to bestow your heart on him! [...] [H]e'd crush you, like a sparrow's egg, Isabella, if he found you a troublesome charge."
In particular, Catherine uses imagery associated with tame birds (a pet canary that couldn't fend for itself outdoors) or defenseless eggs (sparrow eggs are among the tiniest of wild birds' eggs) to warn Isabella that Heathcliff will treat her cruelly, and there will be nothing she can do to protect herself from him. In the same chapter, Nelly, too, advises Isabella to forget about Heathcliff: "He's a bird of bad omen; no mate for you." "Bird of bad omen" is an idiom that means Heathcliff is bad news, auguring a bad future for Isabella. In her more colloquial tone, Nelly builds on Catherine's more picturesque imagery to make clear that Heathcliff isn't the type of "bird" to match the delicate Isabella.
There's additional nature imagery in this passage: Catherine also associates Heathcliff with the wild, uncultivated Yorkshire moors. "Furze" refers to an evergreen shrub (gorse) that's ubiquitous on the moors; whinstone refers to dark, massive rocks common in the North of England. By contrast, Isabella has always been sheltered at Thrushcross Grange and carefully cultivated as a gentleman's daughter. She and Heathcliff are a complete mismatch, and unlike Catherine (whose choice of words suggests she's drawn to the wild moors, like Heathcliff), Isabella can't stand up to his rough, "unreclaimed" nature.
Dramatic irony is also at work in this passage, as readers know that Heathcliff is as bad as Catherine and Nelly say, but must watch Isabella naively blunder into a doomed marriage in the chapters ahead.
Nelly reflects on Cathy's 16th birthday, when she and Cathy were out walking on the moors. She uses imagery conveying youth, promise, joy, and goodness:
She bounded before me, and returned to my side, and was off again like a young greyhound; and, at first, I found plenty of entertainment in listening to the larks singing far and near; and enjoying the sweet, warm sunshine; and watching her, my pet, and my delight, with her golden ringlets flying loose behind, and her bright cheek, as soft and pure in its bloom as a wild rose, and her eyes radiant with cloudless pleasure. She was a happy creature, and an angel, in those days. It’s a pity she could not be content.
Nelly describes Cathy as a "young greyhound," with boundless energy, and remarks affectionately on the young woman's carefree, innocent radiance—the "bright," "wild rose" complexion and "cloudless" happiness in her eyes. The natural environment reflects Cathy's joy, too, with singing larks and pleasant sunshine. Yet this lively, fruitful, promising imagery also foreshadows the loss of Cathy's innocence and freedom. Cathy is fresh and jubilant on the open moor, but she will soon be trapped, stagnant, and bitter as Heathcliff's prisoner at Wuthering Heights.
Given Nelly's perspective, looking back on this memory as she recounts it to Lockwood, the happy day on the moors has a wistful undertone ("She was a happy creature, and an angel [...] It's a pity she could not be content"). Nelly knows that Cathy met Heathcliff and Hareton on the moors that same day, which spelled the beginning of the end of her sheltered happiness. She implies that Cathy's encounter with the men of Wuthering Heights precipitated a loss of her "angelic" innocence, and that it stirred a latent discontentment in her. Her lively curiosity, then, ends up being her downfall, as she starts visiting the Heights and being pulled out of the protective world of the Grange that has fostered her innocence thus far.
Linton and Cathy are comparing their ideas of heaven's happiness and get into a quarrel about it. Their incompatible imagery also sets them up as foils for one another.
He said the pleasantest manner of spending a hot July day was lying from morning till evening on a bank of heath in the middle of the moors, with the bees humming dreamily about among the bloom [...] mine was rocking in a rustling green tree, with a west wind blowing, and bright, white clouds flitting rapidly above [...] and the moors seen at a distance, broken into cool dusky dells [...] and the whole world awake and wild with joy. He wanted all to lie in an ecstacy of peace; I wanted all to sparkle, and dance in a glorious jubilee.
Cathy goes on to say disdainfully that Linton's heaven would be "only half alive," and he retorts that Cathy's would be "drunk."
Linton's image of "bees humming dreamily" among fragrant blossoms is drowsy and hypnotic, while Cathy's image of rocking in the branches of a windblown tree is bright, bracing, and pulsing with life. Notably, Cathy's imagery is more closely akin to the moor itself—wild and untamed. Like her mother Catherine, Cathy finds an expression of her own soul in the "sparkle" and "dance" of nature.
But where Cathy is lively, adventurous, and keen, Linton is weak, unambitious, and content to dream his days away. Though his ideal is also described in terms of nature, it's much more sedentary than Cathy's. The contrast in their ideas of heaven cements what's already apparent—that they're a poor match for each other. They're companions because Heathcliff orchestrated the friendship, but Linton mostly enjoys being doted on by Cathy, and Cathy mostly enjoys babying Linton and bossing him around. If their ideal heavens are so incompatible, then it's hard to see how they would thrive as husband and wife in everyday life on Earth.
At the very end of the novel, Lockwood visits Edgar, Catherine Linton, and Heathcliff's graves. He uses images of gentle vitality to describe what he sees:
I lingered round them, under that benign sky; watched the moths fluttering among the heath, and hare-bells; listened to the soft wind breathing through the grass; and wondered how any one could ever imagine unquiet slumbers, for the sleepers in that quiet earth.
The "benign" sky, fluttering moths, harebells (or bluebells—a common North of England wildflower), and softly "breathing" wind imbue the landscape with life and hope, even in a burial ground. This beauty and fertility contrast with Lockwood's first impressions about the windswept, rather more ominous landscape about a year earlier, when Cathy was trapped at Wuthering Heights with villainous Heathcliff. It's as if the land echoes the repose of its inhabitants, just as it reflected their misery before.
The novel's final words, denying that there could be "unquiet slumbers, for the sleepers in that quiet earth," suggest that after a lifetime of anguish, Catherine and Heathcliff have finally found peace together in death. In light of Hareton and Cathy's impending marriage, the conclusion also hints at a more hopeful future for the people of both Wuthering Heights and Thrushcross Grange, where instead of unfulfilled longing and strife, there might be union and peace.