I Promessi Sposi is set in the seventeenth century, in the Duchy of Milan, then a Spanish possession; it is not a historical novel, even if many events actually took place; rather, it speaks to the present, bearing a distinctly conservative message: we must entrust ourselves to Divine Providence, for we are part of a grand design, incomprehensible to us.
Thus Cardinal Federigo Borromeo explains to Lucia, having just been freed by the Unnamed:

Poor young woman, God has allowed you to be put to a great trial; but He has also shown you that He had not taken His eyes off you, that He had not forgotten you.
He has restored you to safety; and He has used you for a great work, to show great mercy to one man, and to comfort many at the same time

.
The plot, the characters, the prose possess no autonomy of their own; they are subservient to a “morality,” to a vision of society that demands the common people remain quiet, awaiting the salvific intervention of God and His Church.
To each section of the book corresponds a slogan.
The first block of chapters, from I to VIII, is set in a small village near Lecco, recounting the lives of the humble, unwittingly overwhelmed by misfortunes through no fault of their own.
We meet the two protagonists, Renzo and Lucia: the young man a blend of peasant cunning and plebeian impetuousness; the girl a combination of superstitious devotion and apparent docility. Then there are the other characters: Agnese, Lucia’s mother, who embodies peasant common sense; Don Abbondio, the village curate, representative of the moral and character flaws of the lower clergy; Fra Cristoforo, a Capuchin friar with a troubled past, who in turn personifies the torment of a faith hard-won between the urge to rebel and obedience to the Lord; and finally the villain, Don Rodrigo, the symbol of abuse and caprice, of power wielded without justice.
The story is the age-old tale, in the Italian countryside as in so many other lands.
Lucia is the object of Don Rodrigo’s desire, and neither Agnese’s cunning nor Fra Cristoforo’s stratagems are of any avail: Renzo and Lucia must part ways and flee their native village.
Just as the novel opens with the famous description of the mountains around Lecco, wild and pleasant at once, the opening chapters draw to a close with one of the most poignant passages in the entire book.

Farewell, mountains rising from the waters and elevated to the sky, familiar to whoever grew up among you, and impressed upon their mind no less than the features of their closest kin; (...) How sorrowful is the step of one who, raised among you, departs! (...) One who, torn simultaneously from their fondest habits and thwarted in their dearest hopes, leaves those mountains behind to set out in search of strangers whom they never wished to know, unable even in imagination to fix upon a time appointed for return!

Were we to possess even a fraction of this affectionate compassion, perhaps we could face immigration with humanity, rather than letting ourselves be overcome by fear and hatred! The two subsequent chapters, IX and X, recount the story of the Nun of Monza: a young woman forced into a cloistered convent who refuses to accept her fate.
Manzoni speaks to us of the Christian virtue of resignation: failing to entrust herself to faith—and therefore to God’s will—leads the wretched woman to impiety, to the point of betraying Lucia, who had been entrusted to her care, and handing her over to the Unnamed’s bravi.
At times it seems Manzoni is on the verge of plumbing the undeniably conflicted feelings of this wretched woman; then, the writer retreats to a dry biography of the nun and vague psychological sketches, refusing to linger because it serves no purpose for his ends; real life does not interest him; what matters to him is delivering a universal moral lesson.
In chapters XI to XVIII, the narrative turns to the great bread riot that convulsed Milan in 1628, and Renzo's role in it as he naively turns into a popular ringleader.
It is a lengthy digression whose purpose is this: rebellion is futile and harmful, it achieves nothing, and above all, the common people, in their gullibility and fickleness, allow themselves to be duped and are effectively manipulated.
As Renzo will say,

to conduct myself better in the future.
I have learned not to get involved in riots: I have learned not to preach in the public square, I have learned to watch whom I speak to...

We have arrived at what ought to be the novel’s centerpiece: the conversion of the Unnamed, a man so wicked and powerful that people dared not even utter his name,

it signified something irresistible, strange, fabulous...
his life was the subject of popular tales

.
The chapters concerning him run from XIX to XXVII; the plot would have them be the turning point, the struggle between good and evil, with good triumphant: none of the sort.
Federigo Borromeo’s dialogue with the Unnamed is nothing more than a long, cloying sermon by the former, with the latter listening, already defeated before even stepping into the room.
Moreover, the crisis of the Unnamed is not ethical in origin (the consciousness of the evil he has wrought), nor does it stem from an act of love (toward wretched Lucia); at its foundation lie the terror of God and the dread of death.

To grow old! to die, and then? (...) now there rekindled from time to time in his soul the vague yet terrible idea of an individual judgment, of a reason independent of example, (...) the sense of a dreadful solitude.
(...) That God of whom he had heard, but whom for a long time he had cared neither to deny nor acknowledge, (...) he seemed to hear Him shouting within him:
I am, nonetheless

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And this is the meaning of the lengthy chapters recounting the conversion of the Unnamed: to affirm that God exists.
Mind you! Not Christ, who suffered upon the Cross, but the God of the Old Testament, implacable and elusive, before whom one can only bow.
The abstract moralism underpinning the encounter between Federigo and the Unnamed becomes glaringly apparent when one contrasts this exchange with the drama and depth of the chapter "The Grand Inquisitor" in The Brothers Karamazov; there, faith is a torment poised between freedom of conscience and Church-enforced tutelage.
Like the Grand Inquisitor, Manzoni believes that

it is not free decision (...) that matters, nor even love, but mystery, to which [men] must blindly bow, even against their conscience

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Let us return to I Promessi Sposi.

Finally, new events, more sweeping, more potent, more extreme, reached even them, even the lowest among them according to the world’s scale: like a vast, driving, wandering whirlwind, tearing down and uprooting trees, stripping roofs...
(...) searches out in the corners the withered, light leaves that a lesser wind had confined there, and carries them off whirled into its plunder

.
It is the plague (chapters XXVIII through XXXV).
The pivotal chapter is the Thirty-Fourth, which deserves to be read and reread for its evocative power and raw realism.
Manzoni prefaces it with an interesting historical digression, explaining the causes of the epidemic (famine, war, the indifference and incompetence of the authorities, superstition) and delving into the political, cultural, and individual mechanisms that overwhelmed a seemingly well-ordered society.
They are

a confused hum of suppliant voices, (...) a vast, bewildered mass of public folly

, in which only the Church is capable of ministering to the derelict, the sick, and the dying.
And we arrive, finally, at the masterpiece: Renzo enters Milan in search of Lucia, whom he will find unharmed in the lazaretto; the description of his wandering through the Lombard city offers the occasion for a moving fresco of the plague and its victims.

Descending from the threshold of one of those doorways (...) was a woman whose appearance bespoke an advanced, though not bygone, youth, (...) Her gait was weary, yet not faltering; her eyes shed no tears, but bore the mark of having wept many; there was in that grief a certain quiet and profound quality that attested to a soul fully conscious and present in feeling it.
(...) She carried in her arms a little girl of perhaps nine years, dead, yet neatly arranged, her hair parted on her forehead, in a dress of purest white, as though those hands had adorned her for a feast promised long ago and granted as a reward. (...) A foul monatto went to take the child from her arms, (...) "No," she said, "do not touch her for now; I must lay her upon the cart myself"

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This passage, along with many others, bears witness to an empathy so profound as to shatter the frigid moralism; it leads us, without ideological filters, to the suffering of so many peoples, past and present: in Syria, in refugee camps scattered everywhere, to the millions fleeing cruelty and violence.
Here, Manzoni truly rises to the universal, transcending time and space like a Platonic ideal that encapsulates the sorrow of all the wretched of the earth.
After the plague, the subsequent chapters (the final ones, from XXXVI to XXXVIII) amount to very little indeed.
Like a neat fairy tale, everything ends for the best: Renzo and Lucia marry and will live happily ever after.
Troubles befall us, but

trust in God softens them and turns them to account for a better life

.
Is that truly so?

Like many, I read I Promessi Sposi in school and did not like it.
I blamed the obligation and the oral exams.
Re-reading it many years later, I found my initial judgment confirmed: it is a truly dreadful novel.
Its suffocating moralism saps the narrative pace, rendering it tedious and prolix; it fails to breathe life into the characters, who remain stereotypes and often lapse into caricature (such as Don Abbondio); and ultimately, it withers the prose.
Manzoni’s celebrated Italian, held up as a benchmark by grammars, is an artificial tongue.
I am referring not so much to the fact that peasants like Lucia and Renzo speak flawless Italian (fleeing dialect is, regrettably, a constant in our literature), but rather to the extreme use of punctuation, which chops up sentences, weighs down the syntax, and prevents the creation of atmosphere: the prose reduces discourse to mere reportage, accentuates haughtiness, and fails to evoke anything.
To say nothing of the moralizing judgments with which the novel is saturated: let us be frank, Manzoni could have spared us them, for they are truly irritating.

If it is such a dreadful novel, why did it become a pillar of literature? Why not place Fogazzaro, Ippolito Nievo, Federico Tozzi, Collodi, Matilde Serao, and the great Deledda at the center? It would be interesting to see critics answer these questions.
I venture an explanation: I Promessi Sposi mirrors the worldview of the post-unification ruling class, a narrow elite that desired an absent and supine populace.
Manzoni’s novel helped cement this vision, turning it into an undercurrent in our culture from which we have never managed to break free.

Why not read it? Boring, dry, insufferable.

The Betrothed