Henry Cowell: A Man Made of Music by Joel Sachs; Oxford University Press, 300 pages ($45).It was, for decades, forbidden knowledge, acknowledged by precious few who were privy to the Secret History of the 20th Century. And then music critic Donal Henahan, unavoidably, in a review of a Charles Ives biography called "From the Steeples to the Mountains," imparted the news that Ives had a notable falling out with his biographer, composer Henry Cowell, over Cowell's four-year incarceration in San Quentin on a "morals charge" with young boys. Until that moment, it was simply not generally acknowledged throughout American musical culture that one of the true giants of 20th century music in America had been – as we now know – prisoner No. 59182 in San Quentin.

Such once-proprietary information is now a virtual necessity in any notice of one of the greatest of American musical lives. But while Joel Sachs – in this indispensable first major biography – treats the whole episode about as thoroughly as a Cowell biographer could probably stand to do, its sensationalism still must be dwarfed by the rest of the musical significance of this musical (and onetime political) radical.

Not only is it Cowell's piano music that paved the way for John Cage's prepared piano (as well as every American pianist assaulting timid ears with keyboard tone clusters), it is Cowell's earliest investigations of non-Western music – as much as anything else – that presaged almost everyone else's. Cowell's investigations went far beyond Debussy's fascination with Indonesian gamelan into music that would eventually influence Coltrane and the Beatles.

For all its hugely influential experimentalism early on, Cowell was also prodigiously prolific and, as often as not, among the most assimilable composers America ever had.

In addition, he and his wife Sydney were powerful dynamic fixtures of American musical life. Here then, is one of the year's most important musical biographies, an unparalleled book of necessary completeness long overdue about a formidable (and, to be sure, messy) life that was, during his lifetime, as largely unknown and misunderstood as his music was tragically underrated.

– Jeff Simon