Jazz, it's been said, is the sound of surprise, but pianist Reuben Brown has always been something of a constant -- a musician and composer known for his unwavering excellence.

Last spring, however, the 55-year-old District native suffered a stroke that severely affected his left side and silenced -- for now, at least -- his music. Friday night dozens of musicians will gather at the Austrian Embassy to pay and play tribute to Brown, with the proceeds helping to defray the cost of his treatment at the National Rehabilitation Hospital.

For drummer Billy Hart, who attended McKinley High School with Brown, the event has stirred up a lot of fond memories. "I remember going to these assembly programs and watching Reuben play," Hart recalled recently in a phone call from New York. "I guess he was a year ahead of me. I didn't know him then; in fact, I wasn't even playing at the time. All I remember was this superman at the piano. . . . You know, he's always been the kind of musician I just don't understand, like Ray Charles or even Charlie Parker. You just don't know where their talent comes from."

It was no surprise to Hart that Brown soon found himself accompanying world-class musicians on the road. Or that his compositions would later be recorded by Nancy Wilson, Philly Joe Jones and other artists. Eventually Brown and Hart began collaborating, working a steady gig on Ninth Street with Buck Hill and forming a lasting friendship.

"Some people are nice out of a kind of tenderness," Hart noted, "but Reuben has a kind of benevolence that comes from a position of strength. He's a powerful artist and very philosophical -- extremely so -- but he's also very kind. I've only known four or five musicians like that in my life, including John Coltrane."

Like Hill, Brown has been content to live in the Washington area, playing at night and working; before his recent retirement, Brown was a researcher at the National Institutes of Health. His reputation, however, has reached far beyond the District.

"When I went out on the road," Hart recalled, "I found out that everyone knew about Reuben because all of the top players would choose him when they came to town. I mean, Milt Jackson, Stanley Turrentine, Toots Thielemans -- an amazing array of people, the best on the planet. He did everything I did, but he stayed in Washington."

In recent years, Brown could often be heard at One Step Down, where he routinely elevated the level of playing with thoughtfully structured compositions and improvisations. Saxophonist Ron Holloway, who asked Brown to perform on his debut album, "Slanted," regards the pianist's work as "a near-perfect blend of the mind and the heart. You have the intellect, but you also have a lot of warmth and soul."

Ann Mabuchi, who books the talent at One Step Down, concurs, calling Brown a "consummate musician." She's also witnessed firsthand his ability to recognize and nurture budding talent. "It's always a treat for these young players to be exposed to Reuben's style and knowledge," she said.

One of the principal beneficiaries of that exposure has been drummer Winard Harper. In the early '80s it wasn't uncommon for Harper to play on the street in Georgetown, then pack up his drums and head for One Step. "I'd wait for Reuben to break and tell me it was cool to set up," Harper said recently.

"We became very close, and after a while we started to play Monday night trios at the club. . . . We'd talk not just about music but about life. He prepared me to come to New York, to be strong, to stick to my convictions and the path I've chosen for myself."

Now a major-label jazz artist, Harper has recorded several of Brown's compositions, first as a member of the Harper Brothers and more recently on the solo album "Be Yourself." "He's just incredible," said Harper of Brown's gifts as a composer. "He has this extensive harmonic sense and an ability to get right to the beauty of the music."

Among the musicians scheduled to perform at Friday night's benefit are George Coleman, Buster Williams, Barry Harris, Cecil McBee, Steve Novosel, Claudio Roditi, James Williams and Lisa Rich. The Austrian Embassy is at 3524 International Ct. NW. Show time is 7 p.m. Tickets (a $20 donation is requested) are available at the door.