By July first, under the rallying song “All Shall Be Well Together,” more than 250,000 volunteers had joined the construction of the National Altar. Craftsmen, peasants, soldiers, and Parisians—men and women alike—carried shovels and tools as they converged from every corner of the city upon the Champ de Mars in the southwest. Guided patiently by gendarmes and police who volunteered to work overtime, they elected temporary captains, lined themselves into three orderly columns, and marched to the construction site by groups.

  Every patriot toiled with all his strength, shovelling the hardened earth and pushing it away in wheelbarrows. The children came too. Since the site forbade any labour under the age of ten, they maintained order instead, distributing the drinks, fruit, and food sent by local merchants to the workers.

  Mayor Bailly came, and together with his secretary he carried five buckets of water.

  General Lafayette came, and with the aid of a soldier, he raised thirty-five logs upright.

  King Louis XVI and the Queen came as well, bringing five hundred bottles of wine and champagne to the thirsty labourers.

  Every patriot who visited the site worked for at least an hour—no one exempted. They left only when drenched in sweat and covered in soil, yet smiling in deep satisfaction.

  André came too. As the instigator of the entire affair, he had been “escorted” by Robespierre and Prieur from the first day, labouring beside them for three hours each time. After seven exhausting days, by July seventh, the main structure of the National Altar was miraculously finished—an entire week ahead of schedule.

  “I’m going to die,” became André’s first words upon returning home each evening, before collapsing onto the sofa and falling fast asleep. Meldar had to struggle to wake the prosecutor of the Special Fiscal Court for dinner.

  After two days and nights of rest, André finally felt his drained body regain its strength. That was when two invitations arrived—both for salon gatherings.

  The first belonged to the ladies. It had been received on behalf of the Judge’s wife, who now acted as hostess. Since that spring evening in May, André had been meeting her in secret one or two times each week. The vigorous young prosecutor attended to the lonely wife with tireless energy: their “battles” could take place anywhere—carriages, horses, even boats; they had made love amid the trees of the Bois de Boulogne and the Forest of Vincennes more than once.

  The ladies’ salon was held on the ?le Saint-Louis, in Judge Vinault’s garden villa. The Judge himself, a dull man devoid of poetry, never took part in such gatherings—André, therefore, filled the void of a missing master. The women of this circle were wives or sisters of magistrates, prosecutors, and lawyers from the Palais de Justice. Their shared delight lay in conversation about poetry, fashion, and fine food, seldom in politics.

  When André entered the Judge’s wife’s chamber, the room was full of men and women flattering their hostess. A young man was recounting, in jest, the scenes at the Champ de Mars, to bursts of laughter. Sunlight poured through the windows, scattering through a Bohemian crystal chandelier into prismatic colours.

  “I saw a black-robed cleric and a wig-maker in a short tailcoat hoisting a bucket together; a sooty charcoal-burner wrestling over a spade with a fair-faced notary. Bishop Sieyès and Father Maury pretended not to see one another, yet hauled five barrows together. But what moved me most was the loveliest goddess in the thinnest of gowns and a tricolour sash—Paris’s most charming woman, who now sits before me.”

  As he spoke, the young man tried to seize the Judge’s wife’s delicate hand for a kiss—but she withdrew it swiftly.

  The beautiful Madame instantly caught sight of André’s faint smile. Rising from the sofa amid the crowd’s jealous murmurs, she crossed the room, wrapped in a violet fragrance, and softly embraced him.

  Since the Judge’s wife had taken the prosecutor as her lover, André had composed more than a dozen poems in just three months—To the Sea, The Late Blooming Flower, You and Thou, When I Raise My Arm, When I Hold You Tight, My Name, Enough, My Dearest, My Friend, Time Waits for None, If Life Deceives You, and others.

  Though few in number, each was a gem. They circulated among Parisian salons and throughout France. The poem If Life Deceives You crossed the Channel and the Continent—sung in London, Rotterdam, Berlin, Vienna, and Saint Petersburg.

  André had chosen Pushkin’s verses for good reason: the Russian poet had originally written them in French, saving him the toil of translation and rhyme; and besides, Pushkin’s romantic melancholy made a perfect charm for salons—a flawless instrument for seducing discontented wives.

  “Monsieur Franck, the ladies demand a new poem,” said the young man provocatively. He was a lawyer himself, refined and pink-lipped. Although Madame had refused his advances repeatedly, he would not yield, glaring at André with jealous spite.

  Such vermin seldom deserved André’s notice—but if provoked, they were to be crushed. He fixed the red-lipped lawyer with a cold stare. “Who are you?”

  Stolen novel; please report.

  “Merlin-Hil, from one of Lyon’s oldest families, Monsieur le Prosecutor,” the young man declared proudly, puffing his chest.

  “Oh? Never heard of it. Who the hell do you think you are?” André’s arrogance almost drove Merlin to challenge him to a duel. Yet prudence held him back. He knew the prosecutor’s notorious reputation: anyone rash enough to issue a challenge would find, within ten minutes, a squad of patrolmen at his door and a month’s sentence to the stone quarry for “disturbing public order.”

  “André, I too wish to hear your new poem.”

  The hostess intervened just in time to dissolve the tension. She lifted her arm gracefully onto her lover’s shoulder, her bright eyes wandering over André’s athletic frame, her silver earrings trembling in the light.

  André nodded, glancing about the room. On the pink wall, he noticed a bunch of still-fresh French daisies—Marguerites, after which Madame herself was named.

  “To Marguerite.”

  He picked the white flower, inhaled its faint scent, and offered it to Madame Marguerite reclining on her chaise longue, before reciting, with tender fervour:

  “I love you and say nothing,

  only watch you smile across from me.

  I love you—so long as my heart knows,

  I need not know what yours conceals.

  I cherish my secret, and the gentle sadness

  that never turns to pain.

  I swear—I love you while giving you up,

  without hope, yet not without joy:

  to remember you is joy enough.”

  The poem, To Marguerite, was André’s excerpt from Musset’s à Ninon. For lonely women steeped in languid melancholy, such tender sorrow was the most lethal weapon of all.

  Madame Marguerite was indeed moved—her glistening eyes brimmed with tears. When André’s arm brushed against her, she could no longer restrain herself. Rising, she took his hand, and before all eyes the pair slipped away to the attic storeroom.

  Soon, the room filled with the rhythm of heavy breathing and a woman’s sighs.

  It had once been calculated, André mused, that a single act of love equalled twenty minutes of running. By that measure, he had sprinted for over an hour. Still, he remembered he had another appointment. After a hasty farewell to Madame Marguerite, he stepped into his carriage and ordered the driver toward a café near the Académie des Sciences Library in the Jardin des Plantes district.

  It was a scientific salon hosted by Fourier, newly appointed lecturer at the Sorbonne, to thank his friends at the Academy for their support.

  Originally, André had no wish to attend—his ferocious prosecution of the tax farmers had made him unpopular among the learned circles. But he could not refuse Fourier’s plea and promised to arrive at four p.m.

  When the prosecutor entered the library café with Fourier, only a handful of scholars—Laplace, Fourcroy, and a few others—rose to greet him. Out of courtesy, the rest maintained their composure. Though they disliked the prosecutor of the Special Fiscal Court, they offered no open insult. Small groups gathered around a large blackboard, absorbed in some mathematical problem.

  Fourier looked embarrassed. He tried to introduce his patron to the most eminent among them—Academician Condorcet—but Condorcet merely cast a cold glance, turned his back, and ignored André’s outstretched hand.

  “Damn it, do they think I’m a sick cat?” André swore inwardly. Fine. You beat me in calculus and geometry, but in the art of humiliation I can make you suffer for two centuries.

  If force could not prevail, then mischief would.

  Without warning, André strode into the circle, snatched the chalk from a startled professor’s hand, and sketched a rough map of Paris on the blank board—forty-eight districts outlined by quick strokes, each marked with numbers one, two, three, and four.

  In a voice 50 decibels louder than theirs, he silenced the murmurs.

  “An ignorant man like André has a little mathematical riddle for the great minds here. I discovered it at the University of Reims six years ago but have never managed to prove it rigorously.

  I call it the Four-Colour Problem.

  It states that any map can be coloured with only four colours so that no two adjacent regions share the same one. In other words, to avoid confusion, four colours suffice for any map.”

  He took four pieces of chalk—white, red, blue, and yellow—and began colouring the districts. At first the mathematicians watched with amusement. By the twentieth district, their faces grew grave; by the thirtieth, they were calculating in silence; and when all forty-eight were coloured, the room fell utterly still. Every scholar was now absorbed in his own attempt to reason through the puzzle, pencils scratching across paper as numbers filled the air.

  The Four-Colour Problem, later known as the Four-Colour Theorem, would become one of modern mathematics’ three great enigmas. In truth, it had been first proposed in 1852 by an English student—and remained unsolved for over a century and a half.

  Formally stated: “Divide a plane into regions bounded by non-overlapping curves. Each region may be assigned one of four numbers—one, two, three, or four—such that no two regions sharing a common boundary receive the same number.”

  Touching at a single point does not count as adjacency.

  As far as André was concerned, the four-colour puzzle was a perfect tool for intellectual showmanship—simple, elegant, and impossible. In his own century, even supercomputers would need billions of calculations to verify it, hardly the rigorous proof mathematics demanded.

  Dusting the chalk from his hands, André spat lightly toward the floor and looked around with smug satisfaction. Seeing that no one paid him further heed, he turned and walked out.

  He left without taking a cloud with him.

  As he climbed into his carriage, he saw Fourier running breathless behind. Accepting the man’s apology with a smile, André hesitated, then confessed:

  “After today, you and your friends would do well not to lose sleep over this Four-Colour Problem. All right—I admit it. My research over the years has fully proved that it’s insoluble. Just like Goldbach’s Conjecture.”

  But André had underestimated the obsession of mathematicians. Three days later, every scholar and enthusiast in Paris had gone mad over his “Four-Colour Problem.” One enraged tax farmer even offered a reward of 50,000 livres to anyone who could solve the riddle and thus disgrace the prosecutor.