What mystery lies behind this novel that accompanied Thomas Mann throughout his entire life? Begun in 1910 and later abandoned, it was taken up again in 1954, a year before the author's death.
Thomas Mann imagines a singular character—an enchanter or mere charlatan—recounting his life, and does so beginning with an emblematic episode of his youth.
Still a boy, he is taken by his father to the circus, where he marvels at the performance of a renowned clown, whose demeanor, even through varied situations, whether scandalous or comic,

preserved a grace free from all vulgarity and neglect...
free and witty, radiating the joy of life, if one can denote by this expression that exquisite and painful sense of envy, nostalgia, hope, and need for affection ignited in the human soul at the sight of what is beautiful and blithely perfect

.
At the end of the show, the father takes the child backstage to meet the famous clown, and before the boy appears a "revolting sight": a vulgar man, smothered in hideous little pustules, in an atmosphere heavy with ointments and stage paint.

But did the adults, the worldly people who surrendered so willingly, indeed so passionately, to his charms, not know they were being deceived, or, by tacit agreement, did they simply refuse to regard that deception as deceit? Perhaps that was it, when one thinks about it: at what moment does the firefly reveal its true nature—when it glides through the summer night as a poetic spark, or when it squirms in the palm of our hand, reduced to a wretched insect?

The theme is thus that of man's dual personality, of his ambiguous and perpetual disguise, whereby one assumes the guise of whatever pleases: life is a deception practiced upon others and upon oneself.

Felix Krull is the son of a petty German industrialist, a fraudulent producer of counterfeit sparkling wine.
Graceful without being handsome,

fair and dark at once, with the light of blue eyes...
the veiled charm of the voice, the silky sheen of the hair

, Felix would gladly have prolonged the indolent rhythm of his adolescence, had he not been forced, at the age of nineteen, to seek employment following his father's bankruptcy and suicide.
A family friend secures him a post at a grand hotel in Paris.
Here the young man leads a dual existence: lift boy and apprentice waiter during working hours, an elegant and refined Parisian in his leisure time, living off the money of the hotel's wealthy female guests, upon whom he bestows his amorous favors.
He had attained his deepest aspiration, "permutability": merely by changing his attire and his hair, he could be, at will, either servant or gentleman.
It is a life that suits him, until a wealthy young man, infatuated with an operetta singer, proposes that Felix take his place on a voyage around the world, forced upon him by his parents in the hope that he might forget his scandalous mistress.
It is the great leap:

I was seized with a thrill of joy at the thought of the reconciliation between being and semblance that life was willing to grant me, of the appearance that it wished to add to being

.
One might expect a Pirandellian situation; instead, Thomas Mann leads us through philosophical and sociological digressions that overlay the narration of the principal stages of Felix's social conquest.
The first leg of the journey is Lisbon, where the protagonist is readily embraced by high society.
What attracts him in particular are the wife and daughter of the Director of the Science Museum: the former a buxom and rigid noblewoman ("not pretty, but handsome"), the latter a young maiden, "with lips proudly compressed," possessing the typical austerity of the South.
It is the "double image" of feminine allure: haughty nobility alongside graceful, callow youth.
Felix would like to savor both; he even dreams of marriage, but it is the noblewoman who urges him not to "seek fortune in childish fancies" and instead allow himself to be swept away by the "whirlwind of primeval forces" unleashed by a regal, mature bosom.
And here the first part of Felix Krull's memoirs breaks off, leaving us to assume that the young man abandons any pretensions to a solid bourgeois horizon—which is, in any case, precluded by living under an assumed identity—to press on with his life as an adventurer and a swindler.
Yet we shall never know, for the account of Felix's life remains unfinished.

The novel is divided into two parts.
Up until the substitution between Felix and the wealthy youth, we recognize the style of the great Thomas Mann: the narrative unfolds linearly, the treatment of episodes and characters is brilliant, even mildly ironic, and the "caprices" (the digressions, the chronological disruptions, the analytical elaborations) are functional to an overall understanding.
In the second part, the structure of the narrative becomes rambling and disordered.
It is unquestionably clever to relate and gloss the events through the letters of the putative son, Felix, to the putative parents—who are, moreover, bewildered by what is recounted, suspecting, quite rightly, that it is a figment of the imagination.
This literary device demonstrates Mann's mastery, yet it fails to restore the novel to even a minimum of compactness and lucidity.
It seems as though the author is chasing, with the last vestiges of his strength, the completion of a work very dear to him.
Yet his momentum gets the better of him, and an excess of themes and reflections crowd together without order.

Why not read it? It is simply not worth the trouble.

Confessions of Felix Krull, Confidence Man