“Fascinating Rhythm” is more than just the title of a hit song by George Gershwin. It encapsulates the gracefully entrancing, endearingly catchy quality of his songs written for stage and screen like “Lady be Good,” “Let’s Call the Whole Thing Off,” “Nice Work If You Can Get It,” and “‘S Wonderful,” each deservedly a permanent part of American culture. During his brief lifetime — he died of a brain tumor aged 38 — Gershwin, who also wrote “Rhapsody in Blue,” “An American in Paris,”and “Porgy and Bess,”was a physical dynamo, addicted to every imaginable indoor and outdoor sport; his dancing skills were honed to the point where he could suggest dance steps to Fred Astaire. One girlfriend recalled that Gershwin would typically “tap-dance, sometimes with cane in hand, while waiting for elevators.”

This kind of daemonic energy is detailed in “George Gershwin: His Life and Work” (University of California Press, 884 pages, $39.95) by Howard Pollack, a musicologist and professor at the University of Houston, author of the well-received “Aaron Copland: the Life and Work of an Uncommon Man” (1999). Possibly Mr. Pollack’s most important book to date is “Harvard Composers: Walter Piston and His Students, from Elliott Carter to Frederic Rzewski” (1992), celebrating undersung composers of value. As a subject for biography, Gershwin poses the opposite challenge: How to appreciate a musician who is universally cherished?

Mr. Pollack underlines Gershwin’s incessant curiosity and appetite for self-improvement. Even after achieving fame, Gershwin studied music theory, composition, and orchestration, and sought out composers like Ravel and Schoenberg as teachers. Varied instruction made his melodic genius intensify and burn with a purer light. Gershwin’s unified art was posthumously praised by his friend Schoenberg, who said that Gershwin’s melodies are not “products of a combination, nor of a mechanical union, but they are units and therefore not to be taken to pieces.”

Of course, musicologists relish taking any composer’s works to pieces.”George Gershwin” is divided into two parts: “life” and “work.”Yet in reality there is no clear division between these two aspects of Gershwin, and some chapters in the “Life” section, like “Gershwin’s Musical Education to the Rhapsody in Blue (1924)” and “Gershwin and the New Popular Music” — might just as easily pertain to the “Work” section.

Mr. Pollack’s preface strangely suggests that readers may wish to “skim or skip” his long, dutiful plot summaries for Gershwin’s plays and films scattered through the text. In an early chapter, after welcome detail about George’s brother the lyricist Ira, Mr. Pollack describes less relevant descendents who are trustees of Gershwin’s estate. He even pulls a quote from a Chicago Tribune review of a CD made 60 years after Gershwin’s death by a pianist who also happens to be a trustee.

Biographies of this length — more than 700 pages of text plus 200 or so of documentation — tend to be word-processed rather than written, and budgeting space can be a thorny problem. Here fully six pages or so are dedicated to the song “Alexander’s Ragtime Band,” which of course was written by Irving Berlin, not Gershwin. By contrast, some musicological comments here are too succinct to be easily understood, since no musical examples are provided.”The Lost Chord,”a stodgy Victorian ballad by Sir Arthur Sullivan, is puzzlingly claimed as possible inspiration for Gershwin’s winsome “They Can’t Take That Away From Me,”just because “melodies with repeated notes would emerge as a basic impulse for Gershwin.”Gershwin’s mock-minstrel anthem “Swanee” is described as possessing “daffy references to ‘Old Folks at Home,'” a 19th-century Stephen Foster song.”Swanee” is called a “daffy ode to Dixie” later on, although the standard dictionary definition of “daffy” as “crazy” or “foolish” does not seem to be what Mr. Pollack intends. Long, unevaluated lists of Gershwin performances include mention of Lawrence Welk’s TV programs from 1972, which, we are informed in a possible attempt at levity, include commercials for “Geritol, Sominex, Poligrip, and other products aimed at the program’s aging but enthusiastic audience”

Elsewhere, unexplained medical terminology is used in descriptions of Gershwin’s final illness; surgeons removed a “gliomatous cyst as well as a glioblastoma multiforme” and one doctor thinks that Gershwin may have suffered from a “low-grade astrocytoma of many years that degenerated into a fulminating glioblastoma.” Well, that’s show biz!

To fulminate any more about the un-Gershwinlike awkwardness of “George Gershwin” would be ungrateful, since it does make available a vast amount of data. The cumulative impression is of a vitally important composer. Some critics doubted the lasting value of Gershwin’s works during his lifetime, but demanding classical musicians, including imperious conductors like Arturo Toscanini and Fritz Reiner, were persuaded of their worth even then. Mr. Pollack calls “Rhapsody in Blue” “perhaps the best-known concert work of the twentieth century.” Plays and movies for which Gershwin wrote music may have dated aspects now, and even “Porgy and Bess” can be a period piece for many listeners, but Gershwin’s best songs shine with enduring lyric brilliance; “Rhapsody in Blue” and “An American in Paris” will remain joyfully welcome on concert programs and on plentiful recordings the world over — as energetic evidence of the best of what American music can — or once could — offer.

Mr. Ivry is author of biographies of Ravel, Poulenc, and Rimbaud, and the poetry collection “Paradise for the Portuguese Queen.”