For Philippe Cassard, who gives a 50th-birthday recital at the National Concert Hall on Thursday, it is nearly half a lifetime since he took the top prize at the inaugural Dublin International Piano Competition in May 1988. The programme he’s chosen for this week’s recital celebrates Debussy, whose 150th anniversary falls this year and who’s long been a Cassard speciality, and it climaxes with Liszt’s Dante Sonata.

Cassard’s first big recording project was Debussy’s solo piano music – the original label was absorbed by Universal Music, and the recordings were recently reissued as a set on Decca. And last year he released a disc of Debussy with leading French soprano Natalie Dessay that included first recordings of some unknown early songs. Cassard was bequeathed the autographs (the songs have also since been published), and these treasured possessions were the first things he wanted to show me when I arrived for our interview at his home in Vincennes outside Paris.

He played the Dante Sonata in the 1988 competition, but never got to finish it, because he ran over time. Jury chairman John O’Conor rang the notorious bell, forcing him to stop. “I couldn’t play the last three pages, which are the most difficult pages of the piece. So I was probably saved. But I was still furious. John will forever remember my look at him. If I’d had a gun, he would now be in a cemetery.”

His programme sets out to highlight connections between Debussy and Liszt, Chopin and Grieg. Debussy, he explains, “absorbed hundreds of inspirations to become Debussy, including things he hated afterwards. Wagner is the most famous example of official love and official hate.” This influence was still to be felt as late as the opera Pelléas et Mélisande.

Grieg, who Debussy put down as writing “pink bon-bons filled with snow”, played in Paris in the 1880s. And Debussy’s early Ballade of 1890 includes a section that sounds just like a Nocturne by Grieg – a Nocturne which Cassard is also going to play. And the flow goes in the other direction, too. Grieg’s Bell Ringing is a tribute to the new music that he had heard from younger composers in Paris, by Chabrier, Debussy and others.

Chopin is included not just because he was “a hero to Debussy”, but also because the Frenchman’s teacher, Madame Antoinette-Flore Mauté de Fleurville, mother-in-law of Verlaine, “was, or pretended she was, a student of Chopin”. She’s not in any official lists, but maybe she had a lesson at some stage, Cassard suggests kindly.

Either way, she would have heard Chopin, whose playing and method of practising were “the opposite of Liszt’s”.

Liszt stood for “power, stamina, bravura, octaves, two hours a day of pure technique. Chopin studied Bach, had a more sensitive, more sensual way of approaching the keyboard, a fusion between the ear and what comes from the piano. And Debussy is for me the inheritor of Chopin’s way.”

But, as Cassard points out, in 1886 when Debussy was at the Villa Medici in Rome as winner of the Prix de Rome, Liszt came and stayed at the villa, played a number of pieces (including Au bord d’une source, which is in Cassard’s programme), and Debussy and fellow-student Paul Vidal played Liszt’s Faust Symphony on two pianos for the 75-year-old composer. “Thirty years later, in a letter, Debussy says that there were only two pianists who impressed him: his own teacher, Madame Mauté, because of the Chopin connection; and the old Liszt, who used the pedal as if it were a means of breathing.”

The non-narrative evocation of Liszt’s Au bord d’une source, says Cassard, is very close in spirit to what Debussy would later set out to achieve.

So what does he now know about these composers and their music that he didn’t know in 1988? “When you are young, you don’t know anything, but you believe you know everything. In the years before 1988, I was a student in Vienna, where I discovered opera and Lieder. When I went to Vienna in 1982, I thought I knew opera very well, and Lieder, too. Actually, I was completely ignorant. I knew maybe 10 operas. In Vienna, in two years, I heard 65 different operas. I had played and sight-read maybe 50 Lieder. In Vienna, I read two thousand.

“It’s the same now. I could tell you I know everything about Debussy, I have done so much research, read so many books. But, actually, what do I know? A year ago I didn’t know these early songs. Your sensitivity evolves also. You are not the same at 50. It’s banal what I’m saying. But the way I play this music, even Chopin or Liszt, is I hope enriched by everything else which has happened in my life.

“I want to use all my time to get information, about art, life, politics, social life. That’s been my goal. I have tried all my life to get a new energy, to recharge myself. The competition was a major charge. From playing with orchestras, my sound probably improved, the power, the projection . . . the pleasure of being on stage, the way to co-exist with nerves.

“Then there were the chamber music festivals, mostly in the north, in Finland, in Sweden, where I met so many musicians and ensembles. That was another major battery for me. For the next 10 years, I could play with these people, learn new piano quintets, works for piano duet.

Radio star

“Then, almost 10 years ago, I was asked to do a weekly programme on the radio station France Musique. At the beginning I couldn’t imagine how immense, how huge, would be the new knowledge it would bring to me. For each programme I have to read, I have to listen to music, and not only the music I know, but precisely the music I don’t know. My major worry is about routine, about being happy, satisfied with what happens, just doing the same things all the time.”

Back in 1988 he had the passion, but didn’t know yet the level of work his career would demand. “I was quite lazy until the Dublin competition. I practised the piano, I learned my pieces. I found it easy to memorise. Once I won the prize, I realised I had to spend three or four times more time at the piano. It was only then that I realised work would be at the top of my agenda. Working. Working. Working. Working. I did a few concerts when I wasn’t well prepared. It’s a situation you wouldn’t wish on your worst enemy. You feel naked. You feel very guilty. People pay to listen to you. People idealise the artist.

“For a musician, knowing that a country welcomes him year in, year out – in my case, Ireland much more than France – it gives you a comfort, a pillow of confidence. Now, when I play in Ireland, I experience high pressure. I have a regular audience, and I don’t want to disappoint them. I place them very high in my heart. It’s a special satisfaction. And meeting and working with great artists is very special, Natalie Dessay, the conductor Yan-Pascal Tortelier.”

One of his astonishing, ongoing undertakings is to play all of Debussy’s piano music in four recitals over a single day – he did it in Dublin in 1998. “I am very moved, myself, when I do this. I feel the music in my body, in my soul. When people say ‘marathon’, I say, ‘no, poetic journey’.”

PHILLIPE CASSARD ON...

Recordings:'I spend a lot of time doing my recordings. I play many times, I do the montage, the edits. I care about it. For me, the most interesting is the concert, as an interpreter, and as a member of the public. I don't play in my recordings the same way I play in concert. I don't want to play the same. The risk in concerts makes you alive.'

Going to recitals:'It's very boring for me, mostly. What I expect from a concert is something different. You have to take risks, to risk your life, almost. What I find is mostly well-finished, well-made, and nothing more.'

Regrets:'I don't believe people who say they wouldn't change anything. I have paid the price for when I was lazy. It's too late now to learn Rachmaninov's Third, or Messiaen's Vingt Regards. And I feel guilty when I see young pianists playing new music, and I have only done that poorly. I have promised myself to learn pieces by Thomas Adès, Jörg Widmann, and Ligeti.'

Unfulfilled ambitions:'I would really like to play Stravinsky's Les Noces, with its four pianos, the Sonata for Two Pianos and Percussion by Bartók, and Pierre Boulez's Sur Incises for three pianos, three harps, and three percussionists.'

Philippe Cassard's 50th Birthday Recital is at the NCH on Thursday. nch.ie, 01-4170000