ouisa’s lessons began on the second day of the New Year, after their guests had departed.

Since she’d last visited the schoolroom, a bronze model of the solar system had been placed on top of one of the shelves. The easel-like blackboard next to her husband’s desk had been painted with a grid of lines. And though the golden tulips were gone, there was now a large mixed bouquet on the deep windowsill, a splash of color against the greyness of yet another winter day.

In a fawn tweed coat with leather patches on the elbows, the professor arrived exactly on time. He opened his lecture notes, checked his supply of chalk, and tapped one piece of chalk against the painted lines on the easel blackboard. “We’ll start with the Cartesian grid.”

• • •

When Louisa was called to the small blackboard and asked to find various coordinates on the grid, she’d been all too conscious of the shape of his hand at the top of the easel, the way his hair curled at his nape as he reached in to take another piece of chalk, and the scent of the fancy soap they’d been given at Christmas, which made him smell as if he had just taken a stroll, in the snow, across an entire slope of pine and spruce.

But this physical proximity, as dangerous as it was, was not the reason she had resisted and then postponed the lessons for as long as she had. She’d been afraid he might prove to be a good teacher; as it turned out, he was an exceptional one.

A love for his subject, a deep understanding of its intricacies, a logical, orderly progression of topics, and a delivery as charismatic and mesmerizing as any rallying speech from Henry V.

She sat spellbound by this other side of him, the antithesis of the largely smoke-and-mirrors Ideal Gentleman. This was a man who had arrived at his knowledge and competence the honest way—no tricks, no shortcuts, no manipulation of the perception of others.

A man of substance.

An hour flew by.

She left the schoolroom with four pages of sprawling notes and returned to her rooms to see her obviously flushed face in the mirror. It was another hour before she was sufficiently recovered to tackle her homework.

And when she had done so, for reasons that did not exactly make sense, she walked out to her balcony, removed the cover from her telescope, pushed it out to the balustrade, and pointed its nine-and-a-half-inch aperture toward the Roman folly in the distance.

There were once again dress dummies on the belvedere. No, not dress dummies: a single dress dummy, clad in a tweed coat much like those her husband wore around the estate, with a boutonniere pinned to the lapel.

And the boutonniere was none other than a sprig of golden tulip.

I am hopelessly in love with you.

• • •

She was the perfect student.

She was always on time, always ready to learn, and always willing to ask questions. Her notes looked like those of a monkey attempting cuneiform, but her homework was always impeccably neat and almost always completely correct. In fact, she missed only one problem, on the third day of their lessons, and it had vexed her so much that it hadn’t happened again.

However, Felix, by the end of their second lesson, already regretted that he hadn’t hired a tutor for her instead.

She had the most potent gaze in the world.

He could not fault her for looking at him as he described how to graph an equation or calculate the slope of a line—after all, she was supposed to pay attention. And it wasn’t as if she licked her lips, played with her hair, or toyed with the buttons on her blouse. To the contrary, she was indisputably prim and proper, her pen flying across her notebook, her expression serious, sometimes frowning slightly, as she took in his explanations.

And yet, ten minutes into a lecture he would be tumescent. And at the end of a lesson he would be ragingly erect.

It was in the slight part of her lips as she stared at him, the heightening of the color in her cheeks as the minutes passed, the way her left hand gripped onto the edge of her small desk during the latter part of a lesson, as if she were trying to physically restrain herself.

He had to relieve himself with his hand after every lesson. And sometimes another time after she came to show him her homework. During their lessons, he would write problems on the big blackboard for her to solve, and he would find himself standing far too close to her, watching her, and barely holding himself back from pushing her against the blackboard and having his way with her.

All the same, when she asked, after the lessons had gone on for a fortnight, whether she could have two lessons a day, he said yes.

And then immediately locked himself in his bedroom, desperate for relief.

• • •

If he were actually someone hired to tutor her, Louisa would have been doomed.

The purposeful, fluid movements of his wrist as his chalk dashed across the blackboard held her rapt. His perfect freehand circles and parabolas sent frissons of pleasure through her. The talk of quadratic equations, matrices, and inverse functions were so much erotic poetry that set her belly aflutter. And if he even so much as hinted at trigonometry, well, she burned.

If he ever noticed her lust simmering underneath her scholarly attention, he did not remark upon it. And did not let it impair his effectiveness as an instructor.

“As you can see, the relative thinness or fatness of an ellipse is determined by the ratio of distance from focus to distance from directrix, or eccentricity, represented by the Greek letter epsilon.”

She held her breath as a remarkably symmetrical oval appeared on the blackboard, complete with two foci and two directrixes.

“The very nature of the ellipse, the fact that it closes on itself, sets the value of its eccentricity between zero and one, for the foci are never points on the ellipse, and the distance from focus can never be greater than the distance from directrix. But watch what happens when e is equal to one.”

A parabola rose above the x-axis, its two arms perfect mirror images of each other. An unwanted heat began to pool inside her belly.

“Every point on the parabola is equidistant from the focus and the directrix. Now, when e exceeds one, however, a hyperbola results.”

An elegant x materialized, centered on the origin, its four arms extending into infinity. Despite her better intentions, she found herself breathing more rapidly.

“All three of these forms, along with the circle, can be formed by intersecting a plane through a solid cone, as Apollonius of Perga discovered centuries before Christ.”

A fire roared in the room. Afternoon sunlight streamed in from the windows. It was warm. Prodigiously warm. He unbuttoned his morning coat and proceeded to peel it off. Louisa stared.

“Most of his books have been lost. But Conics, which survived, is still considered one of the greatest scientific works of the ancient world and...”

It had been weeks since she last saw his na**d form, the moisture on his skin gleaming in firelight. She wanted to run her hands over him as he whispered the impassioned corollaries of non-Euclidean geometry. Perhaps he would push her onto his desk, sweeping aside all his notebooks as he did so. And she would plunge her hands into his hair—

“Lady Wrenworth,” someone called her, seemingly from the bowels of the manor.

She made no reply. The staff could get by on their own for another half hour.

“Lady Wrenworth!” the voice snapped, along with an explosive noise that almost made her jump out of her chair.

He had slammed a yardstick against the corner of her desk. Her heart thumped with the unexpected ferocity of it.

“Yes?” she squeaked.

He slid the yardstick across the palm of his left hand, a rather malevolent gesture.

“My dear,” he said calmly, “I spend hours every day preparing for these lectures. I have a right to expect respectful attention.”

She swallowed. “I apologize. It won’t happen again.”

He was unappeased. “I doubt that. It isn’t the first time I’ve caught you at it. It isn’t even the first time today.”

Her cheeks scalded. She hung her head.

He sighed softly. “Perhaps I should dismiss class early today, since you cannot seem to concentrate.”

Her gaze flew up. “No, no, please don’t.”

“Then what should I do?”

His voice was most reasonable, yet her knees quaked. Her heart quaked, too, violently. She was the one who had once boasted to him of her ability to endure the deprivation of what she truly wanted. If that were still the case, then she should be able to modulate her voice to something that mimicked his appropriateness, and tell him to continue with the lesson, from the point where the value of the eccentricity exceeded one.

“You should punish me as you see fit, my lord,” she heard herself say, half in dismay, half in... anxiety, as if afraid he wouldn’t.

He leaned against the edge of his desk and crossed his arms before his chest. “When I misbehaved as a child, my tutor would send me to that blackboard”—he indicated the bigger blackboard on the wall—“and make me stand facing it, while he read a magazine.”

She pulled her lips and did as she was told. She supposed some part of her must have hoped that he would tell her to bend over his desk, as they’d laughingly discussed during a different age of the world altogether.

The blackboard was full of ellipses, parabolas, and luscious hyperbolas. She felt as lonely as she ever did in this marriage, standing with her nose almost touching the chalk marks, while the clock on the mantel ticked second by second.

Without being conscious of it, she counted the seconds—fifty-two, fifty-three, fifty-four, fifty-five—as if that would give structure and meaning to an otherwise blank, miserable stretch of time.

“What was it that so diverted you, Lady Wrenworth? You were glassy-eyed, to say the least.” His cool voice came from behind her—directly behind her.

Her misery evaporated all at once, replaced by that state of shattered nerves she’d come to know all too well around him. She picked up a piece of chalk and wrote her answer on the blackboard.

You.

His hand cupped her face. “That is not appropriate for the middle of a lesson.”

She closed her eyes, leaned against him, and lifted her arm to wrap around his neck.

The next second, her skirts were shoved up, her bustle knocked aside, her drawers pushed down not only without ceremony, but with hardly even any acknowledgment that they were ever there.

And then he was inside her, hard and thick.

It was the most incredible, most delicious sensation, like being pounded by a runaway train. The force of his thrusts flattened her. It nearly lifted her off the floor. With one hand on her abdomen, he pulled her toward him, so that he came in farther, deeper, harder.

She cried aloud, her pent-up desires igniting into a fracturing cl**ax, barely noticing that he was shuddering into her, caught in a cl**ax of his own.

Minutes passed before she realized that she was still crushed against the blackboard, and that she had smeared a large portion of his graphs with her torso and her face. But she didn’t care, because by that time he had started to move again inside her, slow, deliberate, gorgeous strokes that drove everything out of her mind except the pure, undiluted pleasure.

• • •

Afterward, he turned her around, kissed her, and wiped the chalk dust from her face. Then he kissed her again. “I would clear the chalk from your blouse, too, but that would require me to do unspeakable violence to your chest.”

She looked down and slapped her hand a few times across her own sternum. A cloud of chalk dust rose between them, surely the most romantic sight in the world, far better than morning mist on the Seine.

When he would have pulled her into his arms again, she walked away, retook her seat, and opened her notebook. He realized after a second that she expected him to pick up where they’d left off.

After a couple of false starts, he did. The class concluded twenty-five minutes late. But other than that, everything proceeded normally: She had a few questions at the end of the class, and then she thanked him and quietly showed herself out.

By the time dinner came around, it was as if nothing had happened. They spoke of the estate, her family, and the weather as it related to the hours of nighttime observation that could be reasonably expected.

Later, however, as he stood in his room, trying to decide whether their lovemaking in the afternoon marked the end of his abstinence or whether it had been simply an aberration, the connecting door opened and she walked in.

His pulse accelerated. “Evening, my dear.”

“We are married, Felix,” she answered. “You should call me Louisa.”

His pulse accelerated further. “Is there a time and a place for it, specifically?”

“Here. And now.” She came toward him and kissed him on his chin. “But it’s only so that I can concentrate in class. We wouldn’t wish to waste your time or disrespect all your wonderfully prepared lectures.”

“No, we wouldn’t,” he answered, cupping her face and kissing her on the mouth.

“So we will take care of all these distractions outside the schoolroom,” she said as he lifted her up to carry her to his bed.

He laid her down and kissed her again. “And we will take care of them thoroughly and tirelessly.”

After that, neither of them said anything for a very long time.

• • •

Have you forgiven me?” he asked, much later.

“Yes.” Louisa combed her hand through his hair. “Or at least enough to once again use you for your young, firm body and your pretty, pretty face.”

He smiled and rested his palm against her cheek. “I’d like you to be happy here. I want to see you discover new stars and whole new galaxies. And I’m still waiting for you to win unimaginable sums playing cards with my friends.”

This last made her laugh a little. “What about you? Don’t you want anything for yourself?”

“I’ve been satisfying my whims my entire adult life. It will not injure me to put aside my self-consideration for a while.”

“I can’t imagine you saying anything like this six months, or even three months ago.”

“I know,” he said simply. “Stay with me tonight.”

“All right.” She’d always meant to, from before she’d opened the connecting door.

“I love you,” he told her, just before he fell asleep.

She remained awake for at least another hour, thinking of him, thinking of their future.