As a child in her native Venezuela, pianist Gabriela Montero displayed such extraordinary musical ability that her path to the world's great concert stages seemed inevitable. Even legendary South American pianist Martha Argerich had heard about the four-year-old who could perform and improvise effortlessly. But Montero wasn't sure about a career in music: "There have been periods when I've studied and played, and others when I've simply given it up," she reveals. "A life in music takes such commitment; it's especially tough when you are a single mom, like me. And I thought there were other things I might like to do. I have a strong humanitarian helper in me, and wanted to study psychology or social work."

All of that changed a few years ago when she visited Ms. Argerich, then performing in Montreal. "I had just quit playing again," recalls Ms. Montero. "She asked to hear me. I said, 'No, let's just have coffee.' But she insisted. I remember it was about 1:00 a.m., and I ran through some standard repertoire and also improvised. Her enthusiasm and encouragement were unbelievable. Something in that moment transformed my life."

Things soon began to click. Concert and recording offers blossomed, and this month Ms. Montero makes her New York Philharmonic debut with Rachmaninoff's Rhapsody on a Theme of Paganini. As it happens, the Rhapsody was not one of the 32 orchestral works in her repertoire, so she agreed to learn it for her Philharmonic debut. But the story doesn't end there: "After I agreed to learn it," she confides, "I got another call, this time from conductor Claudio Abbado. He was in Venezuela and wanted me to perform the Rachmaninoff with him‹immediately! So I actually learned it in three days."

As for those inclinations to serve humanity, Ms. Montero says, "I think I've found a way to fulfill that through my playing."

Stuart Isacoff is editor of the magazine Piano Today and author of Temperament: How Music Became a Battleground for the Great Minds of Western Civilization.