Over the past few decades, classical music has become a rarer and rarer commodity on network television. Gone are the days when Leonard Bernstein would take the New York Philharmonic -- and a rapt audience -- through complicated musical concepts on the deceptively titled "Young People's Concerts" (they were equally instructive for adults). Today, we are lucky to get the Three Tenors vamping their way absentmindedly through "Singin' in the Rain" once or twice a year during fundraising weeks.

Which is why a four-part television series that will be presented by WETA, Channel 26, this weekend and next deserves your attention. The programs, collectively titled "Great Conversations in Music," were commissioned by the Library of Congress and produced and directed by Peter Rosen. They manage to convey some important information about an increasingly neglected art.

The host is Eugene Istomin, a celebrated pianist, a brilliant and cultured man and a Washingtonian of many years standing, who died of cancer in late 2003. He was very sick when he recorded these conversations between December 2001 and March 2003. Yet he brings his customary grace and good humor to the interviews; as one who had the good fortune to dine with the Istomins on several occasions, I can attest that these shows bring back long-ago evenings on Connecticut Avenue as conversations and ideas flowed late into the night.

The first of the programs -- which will air tomorrow at 1:30 -- is titled "The Pianists" and is, overall, probably the best in the series. Istomin is joined by his contemporaries Gary Graffman, Charles Rosen and Leon Fleisher and, from a younger generation, Emanuel Ax and Yefim Bronfman to discuss all aspects of professional pianism -- from how one gets started, through proper and improper ways to play Mozart, through the legacy of Rachmaninoff. (Istomin plays a moment of Rachmaninoff's underrated Piano Concerto No. 4, then adds, "It's cocktail lounge music, except that it's sublime.")

Fleisher remembers practice sessions from when he was a toddler. ("I loved it. I got lots of cookies for it.") Mentors are discussed and appraised; there is much collegial give-and-take and everybody seems to be having a grand time. Among the pianists, it is generally acknowledged that music is a great art and a difficult business, and nobody Istomin talks to would recommend the field without some serious reservations. Rosen sums up the professional criteria: "You only become a pianist if you're not willing to become anything else."

"The Composers" comes next, at 2:30 tomorrow. George Perle and Milton Babbitt, two of our leading modernists, were pushing 90 when this talk was recorded; the panel also includes composer, diarist and critic Ned Rorem (one of Istomin's closest friends); Ellen Taaffe Zwilich (who became the first woman to win the Pulitzer Prize for composition in 1983); and two younger composers, Lowell Lieberman and Richard Danielpour.

This episode does not have quite the same flow as "The Pianists," which seemed an unbroken symposium. Here, we have spliced bits and pieces from Istomin's guests -- but some of those are illuminating. Babbitt offers his creed: "I write the music I like most to hear, and for anybody else who is interested." Rorem says that he was always aware, from earliest youth, that he was a composer, but had to find out exactly what to do about it.

Zwilich mentions that she began composing when she discovered that she found her own improvisations more interesting than "the junk that I was given as a 5-year-old to play on the piano." She also defends popular music from those among her colleagues who would dismiss it all as commercial nonsense: "I'm sure there is an underground of pop music that you don't hear that may be very interesting." (She's right.)

On June 26, two further programs will be telecast back to back: "The Virtuosos" at 1:30 and "The Conductors" at 2:30. "The Conductors" (with Zubin Mehta, James Conlon and Mstislav Rostropovich) is the least interesting in the series: All the interviews are conducted solo, and they don't generally go much deeper than the typical "20 minutes in a hotel suite" platitudes that usually result from brief encounters with the rich and famous.

But "The Virtuosos" is engaging -- a gathering of leading violinists (Pamela Frank, Jaime Laredo and Arnold Steinhardt), cellists (Lynn Harrell, Yo-Yo Ma and Sharon Robinson) and pianists (Claude Frank and Joseph Kalichstein). I particularly enjoyed Pamela Frank's thoughtful, humane and poignant definition of chamber music -- "It's a way to combat loneliness." Many more such nuggets stud "Great Conversations in Music."

"The Pianists" -- the first and perhaps finest of WETA's four "Great Conversations" -- features, clockwise from top left, Leon Fleisher, Eugene Istomin, who is also the host, Gary Graffman and Charles Rosen.