In Book 3, when God appears for the first time, Milton describes him as a "fountain of light"—a rich instance of imagery that also includes a paradox:
Thee Father first they sung omnipotent,
Immutable, immortal, infinite,
Eternal King; thee Author of all being,
Fountain of light, thyself invisible
Amidst the glorious brightness where thou sitt’st
Throned inaccessible, but when thou shad’st
The full blaze of thy beams, and through a cloud
Drawn round about thee like a radiant shrine,
Dark with excessive bright thy skirts appear,
Yet dazzle Heav’n, that brightest Seraphim
Approach not, but with both wings veil their eyes.
God is not even visible on his throne, which is made of "glorious brightness," since he himself is made of blazing "beams," seemingly brighter than the sun, with a "cloud" wrapped around him "like a radiant shrine" (leading Seraphim to cover their eyes with their wings): this imagery is meant to show that God's brilliance, divinity, and authority are unmatched, but also potentially dangerous (the Seraphim could blind themselves if they looked directly at him, as one would from looking at the sun for too long).
Paradoxically, God's robes are "Dark with excessive bright"—in other words, so bright that they appear dark, passing from one end of the spectrum to the other: this paradox both underscores God's brilliance and power, but also shows that not all in Heaven is lightness and serenity. God has a dark side to him, too—as demonstrated by the punishments he enacts against those who disobey him.
In Book 4, as Satan travels from Hell to Paradise, disguised as a good angel, his face involuntarily changes expressions, revealing him to be a fallen angel:
Thus while he spake, each passion dimmed his face
Thrice changed with pale, ire, envy and despair,
Which marred his borrowed visage, and betrayed
Him counterfeit, if any eye beheld.
For Heav’nly minds from such distempers foul
Are ever clear. Whereof he soon aware,
Each perturbation smoothed with outward calm,
Artificer of fraud; and was the first
That practised falsehood under saintly show,
Deep malice to conceal, couched with revenge...
This strange and striking moment (this distinction between good and bad angels and their facial expressions is an invention of Milton's—not founded in any Biblical story) demonstrates Satan's unique complexity as a character (capable of expressing many different kinds of emotions, while good angels have "clear" faces, unperturbed by emotion), and his weakness as a villain: he cannot help but "betray" himself as "counterfeit," and does not realize that his face has changed expressions until it is too late (and Uriel has spotted him).
Emotions, for God and good angels, are negative qualities: they "mar" and "dim" Satan's face, whereas the good angels have no such "distempers foul."
Though Milton's intention in the poem is to "justify the ways of God to men," he portrays God and the good angels as cold and dispassionate; in some ways, it seems understandable that Satan would have sought to rebel against them. Milton seems to be making a broader point about the way power operates—without emotion, and often through punishment and violence—even as he criticizes Satan's own actions.
In Book 5, Adam awakes next to Eve in Eden, and their morning is described with rich imagery (as well as a few allusions):
Now Morn her rosy steps in th’ eastern clime
Advancing, sowed the earth with orient pearl,
When Adam waked, so customed, for his sleep
Was airy light, from pure digestion bred,
And temperate vapours bland, which th’ only sound,
Of leaves and fuming rills, Aurora’s fan,
Lightly dispersed, and the shrill matin song
Of birds on every bough; so much the more
His wonder was to find unwakened Eve
With tresses discomposed, and glowing cheek,
As through unquiet rest: he on his side
Leaning half-raised, with looks of cordial love
Hung over her enamoured, and beheld
Beauty, which whether waking or asleep,
Shot forth peculiar graces; then with voice
Mild, as when Zephyrus on Flora breathes,
Her hand soft touching, whispered thus.
This instance of imagery highlights both the transcendent beauty of Eden—which matches Eve's beauty, drawing a parallel between womankind and the natural world—and hints at the differences between Adam and Eve (in terms of both personality and social status): whereas Adam's sleep is "airy light," and he wakes up feeling calm, Eve has just had a dream in which Satan appeared to her and urged her to eat the forbidden fruit. Eve's tresses are "discomposed," suggesting her susceptibility and wildness—versus Adam's composure and leadership (he wakes up first, while Eve is still engrossed in her dream).
Milton also makes use of a few allusions to Greek poetry/mythology: the "rosy steps" of "Morn" are reminiscent of the "rosy-fingered dawn," an epithet that appears in the Illiad and the Odyssey, and Zephyrus is a Greek god of the west wind who is married to Flora (the goddess of flowers). These allusions further elevate the scene—underscoring the power of both Eden and Eve's beauty.
In Book 5, before the Fall has yet occurred, Milton portrays morning in Eden, using personification at one point to describe the brilliance of the sun:
So all was cleared, and to the field they haste.
But first from under shady arborous roof,
Soon as they forth were come to open sight
Of day-spring, and the sun, who scarce up risen
With wheels yet hov’ring o’er the ocean brim,
Shot parallel to the earth his dewy ray,
Discovering in wide landscape all the east
Of Paradise and Eden’s happy plains...
This imagery is clearly intended to demonstrate Eden's dazzling beauty: as Adam and Eve exit the "shady arborous roof" under which they have been sleeping, the sun greets them, and though "scarce up risen," its rays illuminate all of Eden, immediately transforming night into day.
Milton personifies the sun as a powerful, omnipotent deity of sorts—capable of enlightening the "wide landscape" of Paradise—and thus draws a clear parallel to God: in this prelapsarian world, whose inhabitants God loves unconditionally (since they have not yet disobeyed him), all Adam and Eve know is magnificence. For now, they are free to enjoy "Eden's happy plains," illuminated by the sunlight of God's favor.
In Book 7, Raphael recounts to Adam and Eve how God created the world, using striking imagery and personification to depict the origins of the natural world, while also foreshadowing Eve's eventual fate:
...Let th’ earth
Put forth the verdant grass, herb yielding seed,
And fruit tree yielding fruit after her kind;
Whose seed is in herself upon the earth.
He scarce had said, when the bare earth, till then
Desert and bare, unsightly, unadorned,
Brought forth the tender grass, whose verdure clad
Her universal face with pleasant green,
Then herbs of every leaf, that sudden flow’red
Op’ning their various colours, and made gay
Her bosom smelling sweet: and these scarce blown
Forth flourished thick the clust’ring vine, forth crept
The swelling gourd, up stood the corny reed
Embattled in her field...
By personifying the natural world as a woman—one who gives birth to nature, and is then clothed by nature—Raphael is drawing attention to the fecundity and beauty of the natural world, God's most impressive creation. Additionally, Raphael creates a parallel with Eve, foreshadowing the ultimate consequences of her disobedience. The natural world is "Desert and bare," "unadorned," or naked—like Eve before the fall—and must be clothed in order to be "made gay." Eve, too, will be clothed by the Son of God (in "skins of beasts") after she eats from the Tree of Knowledge and loses her innocence.
Additionally, Raphael's monologue highlights the central role of women in the world. Eve was created after Adam—from a part of his body—and is implicitly inferior to him. Adam serves God, while Eve serves Adam ("He for God only, she for God in him"). But Eve, the "general mother" of humankind, has the capacity to give birth, just as nature gives birth to more nature: "fruit tree yielding fruit after her kind." (In Book 5, Eve is described as having a "fruitful womb" that will "fill the world more numerous with thy sons/Than with these various fruits the trees of God/Have heaped this table.") As Milton makes clear throughout the poem, this capacity lends Eve a kind of supreme power, justifying her position alongside Adam as representatives of God on Earth.
In Book 10, emboldened by Satan's success in Eden, Sin and Death decide to follow Satan to Paradise by building a "broad highway or bridge" over Chaos to Paradise—which is described with striking imagery:
Deep to the roots of Hell the gathered beach
They fastened, and the mole immense wrought on
Over the foaming deep high arched, a bridge
Of length prodigious joining to the wall
Immovable of this now fenceless world
Forfeit to Death; from hence a passage broad,
Smooth, easy, inoffensive down to Hell.
Milton's description of this "prodigious" bridge may seem like a purely fantastical image—consistent with other elaborate descriptions of Hell, Heaven, and Eden's geographies—but importantly, it serves to highlight the consequences of Eve and Adam's transgressions: Eden/the Earth is now directly joined to Hell, which makes it possible for humankind to "smoothly" descend to Hell, now that original sin has been unleashed upon the world.
By depicting Sin and Death as human-like (though clearly monstrous) figures with the capacity to engineer this bridge, Milton renders vivid a key tenet of Christianity: sin and death are not inherent human experiences, but external forces, indeed punishments, leveled against humans to remind them of (and rebuke them for) their capacity for error.
In Book 11, the archangel Michael ushers Adam and Eve out of Paradise and shows Adam visions of future events to come—including striking imagery that tells the story of Noah's Ark (in which a simile is contained):
Meanwhile the south wind rose, and with black wings
Wide hovering, all the clouds together drove
From under heav’n; the hills to their supply
Vapour, and exhalation dusk and moist,
Sent up amain; and now the thickened sky
Like a dark ceiling stood; down rushed the rain
Impetuous, and continued till the earth
No more was seen; the floating vessel swum
Uplifted; and secure with beakèd prow
Rode tilting o’er the waves, all dwellings else
Flood overwhelmed, and them with all their pomp
Deep under water rolled; sea covered sea,
Sea without shore; and in their palaces
Where luxury late reigned, sea-monsters whelped
And stabled; of mankind, so numerous late,
All left, in one small bottom swum embarked.
This intricate description of the great flood (sent by God as a punishment against postlapsarian humans—Noah's ark is the "floating vessel" that survives) makes the consequences and significance of Adam and Eve's disobedience starkly apparent, with phrases that render vivid the scale of the flood—"sea cove[ring] sea," "impetuous" rain, the earth "No more was seen" in the midst of the flooding.
By comparing the "thickened sky" to a "dark ceiling," Milton (describing the image Michael has conjured) is indicating God's absolute authority over humankind: Heaven, in the sky, is the "ceiling" under which mortals live—there is no tier beyond it—and God has the capacity to destroy their world.
Milton's imagery allows the reader to stand in Adam's place: the reader is transported, as Adam has been, to a scene of terror and destruction—which helps the reader to empathize with Adam while also understanding (in a visceral way) the magnitude of God's power.
In Book 12, Adam and Eve are led by Michael out of Paradise for good, a moment Milton renders with poignant imagery:
They looking back, all th’ eastern side beheld
Of Paradise, so late their happy seat,
Waved over by that flaming brand, the gate
With dreadful faces thronged and fiery arms:
Some natural tears they dropped, but wiped them soon;
The world was all before them, where to choose
Their place of rest, and Providence their guide:
They hand in hand with wand’ring steps and slow,
Through Eden took their solitary way.
That Adam and Eve exit Eden with "some natural tears" and "wand'ring steps"—the latter emphasizing their capacity for error, but also resolution and grace ("The world was all before them")—demonstrates that the punishments they have received from God have not led to utter despair and ruination (as Satan intended): instead, they must slowly and carefully make their way through the world to find a "place of rest"—a journey that typifies the human condition.
Also, that Adam and Eve are taking their "solitary" way out of Eden and into the postlapsarian world is significant: though they have lost the relationship with God that they had in Eden (he will no longer speak to them directly), the bond between them has been strengthened (as evidenced by them walking "hand in hand").
