Forty-six years after his death, Henry Louis Mencken remains alive and well to many Baltimoreans, and immensely important to American letters. A new biography -- at least the 15th book about him or his work to be published, if you include his own five autobiographical volumes -- is out this week and is reviewed on today's books pages.

One of the privileges of being committed to write a weekly personal column about books is that I can unashamedly discuss friend and foe alike, so long as I declare my amities or enmities. I could never claim to be objective about this new book or its author. So I won't.

Terry Teachout has been a close and respected colleague of mine for 15 years. He has written often -- and I believe brilliantly -- for these pages of The Sun. He is among my closest friends.

I have watched with delight as Teachout has evolved from a young, but very accomplished, journalist when we first met in 1987. He was a senior editor at Harper's magazine. I hired him as an editorial writer and editor on the New York Daily News, which I served as editorial page editor. Since then -- based on his keen, discerning eye and his command of the English language -- he has become one of the premier critical voices writing in America, with one of the broadest horizons.

Today, he writes regularly, with authority and clarity, about books and often about general culture for The New York Times, The Wall Street Journal, and National Review, as well as The Sun. After 17 years, he continues as music critic of Commentary. For the last five years he has been a regular music critic for Time magazine. He writes a weekly column about New York culture for The Washington Post, and is a regular commentator for National Public Radio.

I am an enthusiastic amateur about art. Years ago, I warned Teachout that one day he would write about painting and sculpture. As I remember it, he declared his interest went no more than millimeters beyond calendars and greeting cards. That was in the early 1990s. In the last two years, he has found himself serially confessing "you told me so"' as his learned articles on art have begun appearing prominently.

And he writes books -- the new Mencken biography, plus a 1991 memoir, City Limits: Memories of a Small-Town Boy, which traced his solid but unexceptional childhood in Cape Girardeau, Mo. He worked his way through college playing bass in a jazz band, and began his career as music critic for The Kansas City Star. From there, he began writing for national magazines. A Terry Teachout Reader will be published in 2003. Meanwhile, he has edited three important books, including A Second Mencken Chrestomathy in 1995.

As the Mencken biography approached publication, I urged Stephen Proctor, who oversees The Sun's features and sports departments, to review it, though there were any number of well-grounded writers -- both academics and journalists -- who would have been delighted to do so. I was particularly eager that he take it on, however, because in the course of my eight years editing these pages and writing this column I have come to find no more clear-eyed enthusiast for Mencken's energy, and for his role in the city and in critical journalism, than Proctor.

In the course of that, Proctor has supplied me with a rich outpouring of Mencken quotes. Perhaps the most irresistible and enduring quality of Mencken's peculiar genius is his quotability. His use of language, both studied and spontaneous, was astonishing -- and continues to be so long after many of the things he wrote about are of diminished or disappeared consequences.

It is hard to read the best of his work without wanting to underscore or to scribble down sentences, even paragraphs. Yet Teachout, who is entirely capable of pyrotechnic phrase-making, served himself and his book well by choosing a narrative voice of almost entirely unadorned directness, with as much simplicity that can be afforded in dealing with a subject as complex and contradictory as Mencken.

It is difficult to argue such restraint by example, but the authority and directness that permeate his book are evident in a passage on Mencken's early volume, The Philosophy of Friedrich Nietzsche. That work, Teachout writes, "tells us rather more about its ebullient author than its enigmatic subject, the prophet of postmodernity who saw the godless future unfolding in his mind's eye, briefly intuiting its hopes and fears before vanishing into the black hole of madness. Mencken was too commonsensical, too solidly grounded in the reporter's world of things as they are, to readily grasp the essence of so tortured a soul. His Nietzsche is an all-American type, a world-improving, can-do go-getter delighted to have seen through the fraud of Christianity and gone beyond good and evil."

The mark of the maturity of Teachout's work is that his fondness for -- his nigh-on devotion to -- Mencken is never compromised. Yet his judgment is clear-eyed and unrelenting. Mencken, in Teachout's assessment, was stuck in time, simply missing modernity as it surrounded him. Born in 1880, Mencken grew into adulthood as Picasso and Braque developed cubism, as architecture and formal music modernism smashed doctrinal bounds. But all that, along with serious dance, jazz and much that was being written, escaped Mencken.

Mencken was a doubt-free agnostic. He scorned all who attested to hopes of improving the lot of humankind. Yet, in his deeply contradictory way, he was a do-gooder himself. Teachout quotes him late in life, as he wrote of death and legacy: "I'll know nothing of it when it happens, but it caresses my ego today to think of men reading me half a century after I am gone. This seems, superficially, to be mere vanity, but it is probably something more. That something is a sound impulse -- the moving force behind all cultural progress -- to take an active hand in the unfolding of human life on this sorry ball. Every man above the level of a clod is impelled to that participation and every such man desires his contribution to last as long as possible."

In a powerfully moving book, Teachout gives fresh new life to Mencken's curmudgeonly but heartfelt hope. I found his biography fascinating because of its comprehension, invigorating because of its clarity, captivating because of its relentless rhythm. But above all, it renders as human Mencken's tragic, perverse and almost blinding brilliance.