Leonard Feather, who passed away on September 22, nine days after his 80th birthday, always insisted that John Hammond was the most important of all jazz critics. That's not surprising if you recall that Feather, who was Hammond's junior by only four years, first made his way through the British jazz world in the early '30s, when Hammond's articles in The Gramophone and Melody Maker were stirring the jazz waters as no English-speaking critic had or would again until Feather himself took up the sword for modern jazz in New York a decade later. Hammond encouraged him to make the move in 1935; 20 years later, he helped midwife publication of Feather's Encyclopedia of Jazz. It was also Hammond with whom he conducted the most vitriolic of several public feuds.

Hammond was the prototype writer-activist, enforcing his pronouncements with a regimen of recording, promoting, producing, and general agitation, mostly on behalf of new talents and new movements - he helped launch the Swing Era. He was also unstinting in his devotion to civil rights, in and out of the music biz. With varying degrees of success, Feather would follow his lead, adding his by no means negligible talents as lyricist (occasionally aided by his wife, Jane) and composer. Indeed, his early years here were devoted almost exclusively to producing, arranging, and composing. Not until the early 1940s, when he became associated with Metronome and Esquire, did he function primarily as a critic.

Yet while Hammond could never entirely disentangle criticism from engagement, and soon fixed himself in the corporate world, Feather - though sometimes tangled himself - had the intellect and independence of the critic born. Over the amazingly long, prolific, and frequently controversial run of his career, he decisively supplanted Hammond as jazz's most important critic and chronicler. That assertion may surprise some who know my own allegiance to Martin Williams, who was often at Leonard's throat, and my distance from Leonard's workaday opinions, which from the mid '60s on could be found mostly in the Los Angeles Times. Yet all of us, even Martin (who contributed to one of Feather's encyclopedia yearbooks), had to acknowledge his work and be grateful for his industry. I would measure his preeminence chiefly on four fronts.

1. His most influential book, the second edition of The Encyclopedia of Jazz, published in 1960 as The New Encyclopedia of Jazz, was and is a cornerstone of jazz historiography. Despite errors (mostly birthdates) and rivals, from Chilton and Grove, it remains indispensable for its critical breadth and autonomy, and for ancillary sections that approach the subject in myriad ways - musicological, sociological, even anthropological. The only book that could possibly supplant it is the one he was completing with Ira Gitler at the time of his death, a biographical encyclopedia, which formatted for the Oxford Companion series, will forgo the editorial apparati and photographs of the Horizon volumes. A singular aspect of Feather's encyclopedias (four volumes and two yearbooks) was the accent on stylistic influence and musicians' perspective; his poll queries attempted to suss out the generational and lateral connections that soon became a constant in jazz criticism. After the original 1955 Encyclopedia, Feather edited two wonderfully revealing year-books that have been published in one volume by Da Capo - check out the study of audience demographics, the history of the record industry, profiles of critics and DJs. More than any other critic, Feather took the subject whole.

2. In 1949, Feather published his first book, a shocking-pink $2 paperback with a tiny picture of his head ("the first critic to herald the new movement in jazz") under the title Inside Be-Bop. It opened, hilariously, with six epigrams eviscerating bebop, including one from Hammond, who at the time found the whole subject of modern jazz anathema. Only 103 pages, it had an incalculable impact, making the case for Charlie Parker and Dizzy Gillespie biographically, historically, and musically, and even by today's standards the transcriptions are exemplary . Feather was, together with Barry Ulanov, one of two esteemed bop heralds. Gitler recalls his early works as humorous, irreverent. In any case, he got the first book out. And though later generations of critics rebuked it and him for missing the boat on Thelonious Monk ( I say he needed a fall guy to underscore the evaluative weight of his endorsement), he captained the ferry that brought Parker and company to port. Inside Be Bop is probably the most plagiarized book ever published about jazz, as Leonard was quick to note. I told him much of the stealing was inadvertent: The book's central ideas passed so quickly into the realm of received wisdom, they were iterated by writers with no idea of their provenance. During the same conversation, I suggested he contact Da Capo about a reprint. When the deal was done, I asked if he would add a new introduction, you know, to clear the air about Monk. He said he'd think about it, but in the end he could concede only that although he might have devalued him, others did the reverse. Another icon he couldn't bear was Jelly Roll Morton.

3. Feather invented the "blind fold test," originally for Metronome and then Down Beat, which copyrighted it - a sore point for him - and continues to publish it. I seem to recall his saying that he did something similar on his popular live-audience radio show, Platterbrains. Eventually, he took a revised and renamed version with him when he joined the staff of Jazz Times. The significance of the blind fold test greatly exceeds its entertainment value. It added a phrase to the language and a new dimension to our understanding of critical authority, demonstrating that people often judged a work of art differently when they didn't know who signed it. Over decades, Feather embarrassed scores of musicians who thought that race and gender were audible, or that studio men can't improvise, or that big names are invariably identifiable. His tests occasionally made news (one with Monk and several with Miles Davis leap to mind), or had a political edge, as when mainstreamers dumped on or defended the avant-garde. Which of us hasn't run the test on ourselves or friends? I fondly recall the evening two colleagues dissed Martial Solal, whom an hour later I slipped onto the turntable - one guessed Art Tatum, the other Cecil Taylor.

4. Not even Hammond championed civil rights more ardently than Feather, especially when he relocated to Los Angeles, and with his great friend Benny Carter as a guide, went to work on Jim Crow in the musicians union and movie studios. His revelations of systematic racism were eye-openers, and instigated important changes. What is perhaps not as well remembered is his service on behalf of women musicians, whom he tirelessly represented in his writings and as a producer. He helped introduce Dinah Washington and Sarah Vaughn; produced all-women jazz ensembles in cooperation with Mary Lou Williams and Beryl Booker, and helped, among several others, Mary Osborn, Vivian Garry, and Vi Redd, who introduced his lyric to "Anthropology" and his canniest blues, "I Remember Bird." One of his wittiest pieces, "Mound Bayou," with lyrics by Andy Razaf, was a minor hit for Helen Humes.

Those accomplishments seem to me paramount, but there were other dimensions to his influence. A careful, clear writer and a solid researcher, he opened a lot of slick magazines up to jazzcrit. He wrote hundreds of liner notes, produced dozens of records (Pre-Bird Mingus and Sonny Rollins Trio and Brass among the classics) and anthologies, consulted on numerous movies and TV shows. He wrote, with Jack Tracy, one of the first and perhaps the funniest of the jazz joke-and-parody books, Laughter From the Hip; his much revised The Book of Jazz, with its endlessly imitated "The Anatomy of Improvisation" and his emphatic tweaking of the New Orleans primitivists, was an academic standby for years. Leonard was a sober writer; sometimes dour; he had little patience with the glib hyperbole that is forever uncovering "perfect" solos and dubbing every musician "jazz's greatest" this or that. As a result, he sometimes appeared exceedingly cool, which is one reason much of his best work can be found in the relaxed personal essays collected in such books as From Satchmo to Miles. As a composer, he was inordinately proud of having written some of the earliest attempts at jazz waltzes and dodecaphony, Those efforts are largely forgotten, but B. B. King still gets his biggest laugh of the night singing the stop-time chorus of Leonard's "How Blue Can You Get?'

I met him in 1975, at Dick Gibson's jazz party, and we saw each other two or three times a year after that. Shortly before our first encounter, I had come across his venomous exchange with Hammond over Duke Ellington's work in the early 1940s, which Hammond scorned, and which Feather represented as publicist. I considered Feather's initial response, "Heil Hammond" (this was 1943, I think), one of the most powerful take-no-prisoners polemics I'd ever read. Yet when I mentioned it to Leonard, he at first denied writing anything with such a headline, and later dismissed it as the gross excess of impetuous youth. In truth, he was never more forceful than when angry, and by the time I got to know him, he was living down a reputation as a tough customer - the guy Muggsy Spanier allegedly cold-cocked before recording "Feather Brain." At the 1975 party, a couple of bop veterans who hadn't encountered him in ages sniped from a distance about his demeanor - beady eyes, watchful of all the musicians out to Muggsy him. But those slights were forgotten when the same musicians could no longer resist rehearsing old times with him, and remark afterward at how much he had mellowed.

He looked mellow enough, and scarily ageless - one of those men who never gain any weight of lose any hair. Tall, reserved, unimposing in manner, he was remarkably steadfast. Well into his seventies, he was driving to the clubs, flying to the festival, sailing on the cruises, and filing review after review with no sign of ennui, though his taste increasingly favored the flashily virtuosic over the expressively idiosyncratic. He was completely focused on music and unapologetically acerbic in his asides. When I last saw him, in the spring, he had begun to weaken, dispirited by the 1993 earthquake that forced him and Jane to vacate their Sherman Oaks home. In a coma for most of the past month, he went out with his boots on - not with a pen in his hand, but with Benny Carter at his hospital bedside day after day, playing jazz records.