Pianist Pierre-Laurent Aimard says that at the start, his sabbatical time was improvised, but then he felt that he needed a kind of discipline. (Marco Borggreve)

Pierre-Laurent Aimard is a thinker at the piano and a champion of contemporary music. Not until six years ago, already well-established in his career, did he make his first foray into Bach with “ The Art of Fugue .” Now, he has returned to that composer; he is touring with Book I of “The Well-Tempered Clavier” after taking a sabbatical from performing to immerse himself in the music. On Friday, he is coming to the Library of Congress with a program focusing on fugues, juxtaposing pieces from “The Well-Tempered Clavier” with works by Beethoven and Brahms. Last month, he spoke on the phone about Bach, about taking time off from performing and about his new baby, Arthur, born in August, with Tamara Stefanovich , an adventurous pianist in her own right.

On his sabbatical: “I planned a sabbatical years ago. It came at exactly the right moment. The goal was to have time, [to] give time to time. In an organized life, on tour or not, you always have to be somewhere [at a certain time]. . . . I needed a different way to live, to be at the disposal of this music.

“At the start, I thought that, because life with concerts is so organized nowadays — [you know] two years in advance where you will be, which flights you will take — I thought [the sabbatical] should be completely improvised: You read books if you want, you travel if you want. Then I thought, I have to have a kind of discipline. . . . And then I got a chance to be at the Wissenschaftskolleg Berlin. So I lived there for a season with an incredibly stimulating company of experts in all possible fields: biologists, historians, sociologists, writers. . . . I lived there in a small house with a garden in front of the library. I was alone in this house; I had an instrument; I could play day and night — in fact I could play only when it was the right moment. I did play, and with a lot of pleasure. But I did a lot of other things: met a lot of fellows, attended conferences and went a lot to concerts, the theater, the opera. . . . This was extraordinary. I had the feeling of starting a new life. Sincerely, I was a little afraid; there were moments when I thought, if I could, I would remain like that for the rest of my life. . . . And now I think I play with more joy and lack of any doubt than ever, well, maybe when I was very young.”

On playing “The Well-Tempered Clavier”: “I always knew that if one day I would play Bach, it would be ‘Art of Fugue’ because it’s such an enigma, such a challenge; this piece is a question mark for the interpreter. But it was very hard. And it seemed to me that every concert was just impossible, to climb the mountain. And now with the ‘Well-Tempered Clavier’: Maybe it’s much easier, maybe less challenging; maybe the piece is more seductive with all these different keys, with all the preludes. Maybe also it’s the piece of a younger man. And maybe, simply speaking, I had lived with many of these pieces when I was young. It seemed to me always joy, and never pain. . . . Each concert is one moment of grace; I say thank you every time. I have the feeling that it changed my life, my musical life as well. Because I think this was the moment when I needed this breath, some freedom, some peace. After all, this is a piece that has not been composed for the concert [stage]. So somehow you have no stage duty. I don’t have to prove that I’m a good pianist. You just have to be in contact with this music as right[ly] as possible, as sincerely as possible, as generously as possible.

“I didn’t touch Book II. That’s the next sabbatical.”

On choosing a piano to play Bach: “When Bach said ‘well-tempered,’ it did not mean equal like today. It was just more balanced than traditional playing. We can tolerate modern tuning. The problem is more for me the type of calibration you will ask for your instrument in order to have an instrument that can work for Baroque style. An instrument that is registered for Rachmaninoff will be a disaster for Bach. You need for Baroque music an instrument that articulates very well, that is very clear, with very explosive attack and clear attack, and if possible an instrument that sings very well without using the pedal. Then you can start working. But there is still a lot of work.

“Before making this tour, I was terrorized about the instrument I will have for it. I thought, ‘I will never have the right instrument; it will be terrible.’ And I think there has never been a tour where I have been happy so often. And why? First of all, we are not playing the instrument that Bach has written for in any case. Second of all, because of that you put your work into something else than purely pianistic potential: the articulation, the polyphony, etc. And that you can use everywhere.

“At the end, surprisingly, I’m happy. Maybe thanks to the sabbatical I’m a more happy man now. And maybe because of Arthur.”

Pierre-Laurent Aimard performs Bach, Beethoven and Brahms at the Library of Congress’s Coolidge Auditorium on Friday at 8 p.m.