1In Paris, in the last days of the old king, a baron had a daughter who could do sums in her head faster than his steward could do them on paper. Her name was Émilie.
2Her mother wished her taught to curtsey, to keep her eyes down, and to speak when spoken to. Her father, who was fond and a little vain of her, let her have a Latin master instead, and geometry, and the run of his library. It was thought a harmless folly. A girl's learning was like a girl's lapdog: a pretty thing, and no one supposed it would hunt.
3They married her at eighteen to a marquis, a soldier, a decent, dull man who was away at the wars nine months in twelve. She bore him three children. She went to court. She played cards for high stakes and won, for she could count what had been played and reckon what remained, and she spent what she won on books.
4But she was hungry in a way the court could not feed. There was a new learning abroad, the learning of the turning sky. The Englishman Newton had bound the moon and the falling apple in one law, and all Europe was quarrelling over it. Émilie wished to understand that law, and not from an abridgement made for ladies.
5Hear what doors were shut to her. The university took no women. The king's Academy of Sciences took no women, not to sit, not to listen. There was a coffee house in Paris where the mathematicians met to argue. She walked in one afternoon to join a friend at his table, and the master of the house came and told her that ladies were not served, and showed her the street.
6It is told that she went home, had a suit of men's clothes made, and came back the next week in coat and breeches. Everyone in the room knew her. No one was deceived for an instant. But the rule said no ladies, and here was a person in breeches, and the master of the house brought the coffee. She sat there after that whenever she liked.
7She hired the best mathematicians of the Academy to teach her in her own rooms, and paid them, and worked until she could dispute with them.
8Then a poet came into her life, and trouble came with him.
9He was called Voltaire. He was thin, quick, vain, kind, and could not see a sacred cow without wishing to prod it. He had been twice locked in the Bastille for his pen. He had lived in exile in England, where he had watched Newton carried to his grave among kings, and had marvelled that a people should bury a reckoner so. He came home and wrote a little book praising English liberty and English science. The court had it torn and burned by the hangman on the steps of the law house, and a warrant went out for the author.
10Émilie hid him. Her husband owned a crumbling house far off in the east, at Cirey, among forests and iron forges, a short ride from the border. If the king's men came by the front road, a man could be out the back and into another prince's land before they had the gate open. She sent the poet there. Then, to the wonder of all Paris, she left the court and followed him.
11They lived at Cirey for most of fifteen years. They mended the roof. They filled a gallery with instruments: air pumps, prisms, a telescope, scales fine enough to weigh a breath. They gathered more books than some universities owned. They met at supper and talked till midnight, and all the rest of the day each one worked behind a closed door. It was, for a time, one of the places in the world where the fire burned brightest.
12Now hear about the prize.
13The Academy in Paris set a question for all the learned of Europe, with a purse for the best answer. The question was the oldest there is. What is fire, and how does it spread?
14Voltaire resolved to win it. He was a poet, but he would show them he was a natural philosopher too. And he had a plan. If fire is a kind of matter, he reasoned, it must have weight. So a thing full of fire must weigh more than the same thing cold.
15He went down to the marquis's forges in the forest. He had the smiths heat great masses of iron, a thousand pounds and two thousand, until they glowed white, and haul them with chains onto a scale; and then he had them weighed again when they were cold. Émilie stood beside him in the roar and the sparks with a slate, writing down the numbers.
16The numbers would not behave. Sometimes the hot iron weighed a little more, sometimes a little less, sometimes the same. Voltaire looked at them and saw what he had hoped to see. He wrote his essay: fire is matter, and it has weight.
17Émilie looked at the same slate and did not see it. She thought the numbers said the opposite. She thought fire had no weight at all, and was not matter as iron is matter. She told him so. He laughed, and kissed her hand, and went on writing.
18She could not argue it out with him. He was a great man, and it was his prize, and besides he could talk her down in any quarrel by sheer speed. So she did a thing no one expected. One month before the day the essays were due, she began an essay of her own, and told no one in the house but her husband.
19She wrote it at night. By day she was the lady of Cirey and the poet's helper at the forge. When the house slept, she lit her candles and sat down to answer what fire was. She slept one hour in a night. When her head began to fall, she plunged her hands to the wrists in a basin of cold water, and walked up and down the room beating her arms against her sides, and sat down again.
20She had no time for new trials at the forge, and she could not have made them unseen. She had only what was known, and her own reason. With these she built her case in more than a hundred pages. And in the midst of it she set down a guess that was sixty years before its time. The light of the sun, she wrote, is made of many colours, as Newton had shown. Might not each colour carry a different share of heat? Might there not be rays that warm more than others, if one could only measure them?
21She sent it to Paris under a number, with no name, as the rule required. Voltaire sent his. Neither knew the other had written.
22Neither won. The purse was divided among three others, one of them the great Euler. When the news came to Cirey, Émilie told Voltaire what she had done.
23Mark what he did, for it is to his honour, and he had his share of faults. He was the most famous writer in Europe, and his lady had gone behind his back to contradict him before the Academy. A smaller man would have sulked for a year. Voltaire read her essay through, and praised it to everyone, and sat down and wrote to the Academy asking that both be printed with the winners.
24They were. It was the first time the Academy of Sciences of France had ever put into print the work of a woman. It could not seat her. It could not let her in at the door to hear her own pages read. But there they were, with her name on them.
25After that she did not hide again. She wrote a book of the foundations of physics, in plain French, for her young son, so that he should not have to climb the wall she had climbed. And in it she took up a quarrel that had split the learned for fifty years.
26The followers of Newton reckoned the force of a moving body in one way. The followers of the German, Leibniz, the duke's librarian in the great wig, reckoned it in another. Leibniz had said that there is a living force in a moving thing, and that it grows as the speed multiplied by itself. Double the speed, and the force is not doubled but made four times as great. The English mocked this as German fog.
27Émilie knew of a trial made by a Dutchman. He had let brass balls fall into a tray of soft clay. A ball that struck at twice the speed did not go twice as deep. It went four times as deep. She saw that this settled it. Leibniz was right about the living force, and Newton was right about nearly everything else, and a mind that would not take truth from both sides of the water was only keeping a party. She said so in print.
28Then she began her great work. Newton's book of the laws of the sky was in Latin, and it was hard even for those who had the Latin. She would put the whole of it into French, and add a commentary that carried it forward with the newer reckoning of Leibniz, so that all France might read the law of the heavens. It was a labour of years. She was still deep in it at forty-two.
29In the winter of that year she found she was with child.
30She was not a fool, and she did not tell herself tales. Women of that age did not often rise from childbed. She looked at the number of her years and at what she knew of physic, and she reckoned her chance as she would have reckoned a hand of cards, and it was not a good one. She wrote to a friend that she feared she would not live.
31She had perhaps eight months. The Newton was not half done.
32So she walked the dark road before night, in the old way. She looked straight at the thing that was coming, and asked what could be finished before it came. She set her house in order. Then she made herself a rule of hours and kept it like a soldier.
33She rose at eight and worked until three. She took coffee, and worked from four until ten. She stopped then, and supped, and talked with Voltaire until midnight, for she would not give that up. At midnight she took up her pen again and worked until five in the morning. She slept three hours. She did this through the spring and the summer, while the child grew heavy in her.
34Voltaire begged her to rest. Her friends told her she was killing herself. She said that if she rested the book would die and she perhaps as well, and if she worked the book at least would live. She had lost too many years already to curtseys.
35In the summer the household went to the court of a kindly old duke in Lorraine, where she was to lie in. She worked there at a table by the window, with the proofs of the sky spread round her. In the last days of August she wrote the final page of the commentary. She had the whole of it tied up and sent to Paris, to the keeper of the king's library, with a letter asking him to enter it in his book and keep it safe, so that it should not be lost. She dated the letter. It is still there.
36A few days after, at her writing table, her pains began. The child was a girl, and came easily. Voltaire wrote to their friends that the lady had been delivered while scribbling at her Newton, and that the infant had been laid on a book of geometry while they looked for a cradle. Everyone laughed, and breathed again.
37On the sixth night she took a fever. It is told that she asked for her manuscript to be brought, and wrote the day's date on it with her own hand. Then she slept, and toward midnight her breathing changed, and before those in the room well understood it, the Last Door had closed.
38Voltaire walked out of the room like a man struck blind. He got as far as the foot of the great staircase and fell there, and lay with his head against the stone sentry box by the door. They lifted him up. He wrote afterward that he had lost the half of himself. The little girl lived less than two years.
39But the book lived. It was printed entire ten years after her death. And see how the Weave fell out. That was the very year when a comet came back into the sky of Europe, on the road and near the hour that had been reckoned for it long before from Newton's laws. People stood in the fields of France and watched it rise, and those who wished to know why it had come as foretold could go indoors and read the reason in their own tongue, in her words.
40It is the French Newton still. In all the years since, no one has made another. Whoever in that country has gone to the root of the law of the heavens has gone by the road she finished in the last week of her life.
41And her guess about the colours of light and their heat? Fifty years after she died, a man laid a thermometer in the rainbow cast by a prism, and found that the colours did not warm it alike; and that past the red end, where the eye saw nothing, the glass rose highest of all. She had not lived to see it. She had only left the door standing.
42The Academy that printed her would not have let her through its gate. Think on that. She had the same fire in her as Euler had, or Newton, and it was fed on scraps and stolen hours and had to wear breeches to buy a cup of coffee. How many such fires were there in France in those days, behind how many lowered eyes? No one counted. No one thought there was anything to count.
43Voltaire did not marry. He grew old, and rich, and more famous than kings. He bought a house on the border of Geneva, with a garden, and he thought he would spend what was left of his life growing lettuces and writing plays.
44But he had learned something at Cirey, at the foot of a staircase. Now hear what he did with it, when a young man came over the mountains to his gate with a story no one in France wished to hear.