IT STARTS OFF with a bang: a triumphant C major chord, its root, third, and fifth voiced across the entire orchestra. It’s as if you came home from a long day at work, entered your home to find the lights out then suddenly on, and a group of fashionable 18th-century Viennese men and women shouting in unison: “Surprise!”

Welcome to Mozart’s Piano Concerto No. 25, a long and winding journey through high-stepping rhythms, unexpected key changes, judicious use of pauses and silence, and melodies that unspool with an uncanny inevitability. On March 22, 23 and 24, celebrated pianist Emanuel Ax will perform the concerto with the Houston Symphony, on a program that includes Beethoven’s “Eroica,” a.k.a. Symphony No. 3, and Missy Mazzoli’s These Worlds In Us, a uniquely orchestrated tone poem inspired by James Tate’s The Lost Pilot and dedicated to Mazzoli’s father, a veteran of the Vietnam war.

Before taking the stage with the HSO, Ax will play a free recital on March 21 at MD Anderson Cancer Center, as part of the center’s free Music-in-Medicine Concerts in the Park series. The title of the program is The Art of Musical Healing: A Piano Recital and is part of the center’s Music-in-Medicine Initiative, which explores how listening to music improves health and wellness. (In 2020, during the COVID-19 pandemic, Ax volunteered his time to perform virtually for MD Anderson’s ICU patients on Zoom.)

Although he hasn’t investigated the specific medical and psychological benefits of playing and listening to music, Ax describes the Music-in-Medicine program, a selection of Beethoven sonatas, as “ennobling and hopeful.” “He had a dreadful life in so many ways,” says Ax, “and yet he turned out music that was just hopeful. I think his music is very life-affirming.”

Ax, who is 74, vividly remembers playing the Mozart concerto at the Mostly Mozart festival in 1975 but blanks out when asked if he was happy with his performance. “I hope it was all right!” laughs Ax. “I’m not a good judge of myself. I assume most of the time I don’t play very well.”

But isn’t Mozart fun to play?

“It’s quite scary,” says Ax. “The music is unbelievably wonderful, but there’s not a lot of room for error.” He recalls F. Murray Abraham as Antonio Salieri in the 1984 film Amadeus describing Mozart’s music. (“Displace one note, and there would be diminishment. Displace one phrase, and the structure would fall.”) “You have to get things quite right, and it’s just hard to do,” says Ax. “But the music is so great, it’s worth it to keep trying.”

Ax responds with an adamant “No!” when asked if he’s grown tired of playing Mozart and compares his relationship with the music to his own marriage of 50 years. “It’s like what you feel about anything else that you love,” says Ax. “It’s not that you feel more deeply or differently about your partner. You see different things. I’m still in love, but just in a different way. That’s how I feel about Mozart too.”