At its best, an interview with a person of any depth or complexity is like a snapshot; one intrudes for a moment on a constantly shifting reality, looks around briefly and sets down impressions that might have been quite different a week earlier and certainly would not be the same five or 10 years later.

Sometimes, the images in Elyse Mach's interviews with 13 notable pianists seem to reflect a fairly permanent reality -- Lili Kraus as a woman hopelessly in love with Mozart, Claudio Arrau and Alfred Brendel as Renaissance men who happen to have settled on music as their chief interest, Glenn Gould as a man intrigued by musical ideas who uses the piano to work them out because it it convenient and he is good at it -- a pianist, so to speak, who follows a different drummer.

But one wonders whether John Browning comes across as the consummate technician because he was interviewed just before giving a master class, or Vladimir Ashkenazy is shown as a hard worker but essentially, in his own words, "pretty dull," because that was how he happened to be feeling that day.

An interview is also like an image glimpsed in a mirror; no matter how hard the interviewer tries to be neutral and totally receptive, to let the subjects "speak for themselves," as this book's title claims, any interview records an interaction of personalities. The conversation tends to ricochet between two sets of interests, and its quality depends in some measure on the interviewer's contribution.

Mach seems to know quite a bit about the piano and not much about the intricate art of the interview or the arrangement of written material in a smooth, logical sequence. She does not write particularly well, and one assumes from the context that she must occasionally ask rather pointless questions. The questions are not usually printed in this volume, but they can be deduced from such answers as "I have no pet superstitions or good luck charms." All of the pianists in the book seem to have been asked what historic period they would like to have lived in and which notable composers they would like to have known personally -- the sort of question one might expect from a journalism student who comes to the interview with a written list of questions in hand.

In spite of these rather severe handicaps, she has produced a book of uncommon interest -- for pianists and serious music-lovers, if not for the "wide audience" which is her target -- simply because she has managed to corral some of the world's most interesting artist and sit them down in front of a tape recorder.

Much of the information is banal. One can learn, for example, that Ashkenazy practices five to seven hours a day when he is not performing regularly in public, that Brendel practices about five, Arrau not more than three and Gould hardly at all -- but that is not really matter to justify the bother of making (or buying) a book. More interesting are the occasional remarks made in passing, such as Byron Janis remembering that Horowitz told him at the end of their student-teacher relationship: "You'll go out and make mistakes, but that's okay; they'll be your mistakes. Let them be yours. Say something with your music; it doesn't matter what, but say something that's you ."

As Janis quotes Horowitz, Horowitz quotes Rachmaninoff and Prokofiev. He recalls Rachmaninoff's answer to a fan who asked him what inspired him to write his Sceond Concerto: "Twenty-five rubles." And Prokofiev's brass-tacks critque of his own Second Concerto: "Don't play the Second. It has too many notes." But Horowitz also speaks, as the title promises, for himself: "The most important thing is to make a percussive instrument a singing instrument," he says, and he even offers a hint or two on how to do it. sEchoes of his advice to Janis can be found in his remark that "the pianist should never be afraid to take risks," and his complaint that "There seems to be an element of sameness in many pianists today. It is difficult at times to distinquish one pianist from the other."

Most of the pianists in this volume are easy to distinguish from one another because they are not only notable artists but well-developed personalities. Glenn Gould is outstanding in this respect, of course, and he tackles head-on the question of whether he is "eccentric": "I don't think that my life style is like most other people's and I'm rather glad for that." Whether his eccentricity is the reason or not, Mach departs from her usual style by printing the questions asked in his interview, which is probably the most interesting in the book. (The Horowitz interview, a close second for interest, also has frequent italic inserts that indicate what questions were asked.)

Some of Gould's remarks are personal: "I used to take my pulse rate just before a concert out of scientific curiosity, and it was always very fast. So there was obviously a kind of unnatural excitment. But it wasn't the sort that paralyzed me with fear, if only because I had a kind of indifference to the whole process." Others are uncannily perceptive: "There are, all other aspects notwithstanding, certainsimilarities between [Barbra] Streisand and [Elizabeth] Schwarzkopf. I think they're both, first of all, italicizers." Some blend wit and musicology: "I'm not a die-hard believer in the twelve-tone system . . . I tend to admire Schoenberg in spite of it rather than because of it. But it did, undeniably, satisfy the Germanic urge toward what one might call visual as well as aural coherence in music and, perhaps for that reason, it made Schoenberg, if only temporarily, a very happy man."

Such remarks may appeal to a very specialized kind of interest -- more specialized than Brandel's remark that "Once a conductor is past seventy, there's little good in arguing with him" or Ashkenazy's comment that the Russians train their musicians the same way they train their athletes "so that they are well-prepared and win prizes . . I tend to think that Russia creates good musical sportsmen rather than great artists."

As these quotations indicate, Mach has produced a far-ranging book, although one firmly centered on the piano and people who have dedicated their lives to it. Its interest lies most often in hints and fragments of personalities and ideas, rather than in thoroughly developed and well-rounded discussions. For this reason, its value will depend largely on what the individual reader will bring to it -- but that value is nonetheless real and significant.