For 40 years I have been a book reviewer. In that time I have read numberless biographies of and novels by American writers who pursued their craft in the 20th century, an age in which it is always said (and with truth) that the social atmosphere was (and is) poisoned with the foul air of antisemitism. I know of four major novelists who portrayed Jews with some venom (of course, there may be others): Edith Wharton in "The House of Mirth," Ernest Hemingway in "The Sun Also Rises," F. Scott Fitzgerald in "The Great Gatsby" and Willa Cather, whose animus is evident in some early sketches, in two short stories written after her beloved friend married a Jewish musician, and in "The Professors' House," in which a major character is most offensive, and Jewish.

Two poets (both expatriates) were antisemitic: Ezra Pound and T. S. Eliot.

Seven creative writers who were not immune to the vicious virus in the American air, out of the thousands who were writing, is a small number, making one wonder why, if the attitude was so acceptable and so persuasive, the myriad others were not similarly affected. There is no excuse for the seven, surely (although The Post's book critic believes "we do no man of an earlier time justice if we judge him by the standards of our own more enlightened age" {Style, Dec. 11}), but there is far less excuse for a highly influential journalist such as H. L. Mencken, whose work was not so much a reflection of what he might have thought he saw in society (like Lily Barth's suitor in the Wharton novel) as it was a potentially influential contribution to creating that social atmosphere.

Mencken asked that his diaries be withheld from publication until 25 years after his death. Now we have them, or at least, one-third of them (I shudder to think what nastiness the editor has withheld from us in the other two-thirds), and we can learn once again of the Sage of Baltimore's mean-spirited intolerance on many subjects: mill-workers, whom he calls "lintheads"; blacks; Eleanor and Franklin Roosevelt and all Roosevelt's Cabinet and advisers; historians ("if any good ones ever appear in America"); his neighbors ("complete morons"); a few Methodists; a few Catholics; his writer-friends, who are almost without exception portrayed as drunks, fools, mad or incompetent; Winston Churchill; women writers; women; doctors; lawyers; other journalists.

But far and away the strongest bigotry is against Jews. There are 24 racial labels, attributed stories and direct insults in the recently published diaries. Some seem to be intended as journalistic accuracy: "Lawrence Spivak is a young Harvard Jew"; Charles Angoff, "like most of the young Jewish intellectuals"; Simon Sobeloff of Baltimore, "a smart Jew"; George Boas of Johns Hopkins, "a brisk, clever Jew"; Morris Fishbein, a "shrewd Jew."

Sometimes Mencken uses the hated designation inaccurately for a whole group: Sinclair Lewis wanted to sell a novel to Hollywood: "The Jews have offered him $30,000." Communists are all Jews, the International Ladies Garment Workers Union (he quotes a Mrs. Reed, who headed a garment factory) is operated by New York Jews. He speaks to a club in Baltimore and is angry at the questions directed to him. "Most of the questioners were radicals and it was apparent, in the rather dim light, that most of them were Jews." Union members are all "Jewish communists." Mencken seems pleased to be able to record that Johns Hopkins turned down an offer to have the Institute for Advanced Study on its campus because "the donors were Jews." The quality of a Baltimore distillery's product deteriorated after it was bought by Jews.

Sometimes he is uncertain, perhaps because the name is not indicative, but still, he wishes to make clear his suspicions: James Hunecker's wife Josephine, "who I believe is a Jew"; Julius Haldeman, "a highly dubious Jew"; and Sinclair Lewis's new wife, who, he suggests, is hiding her true identity. "She is a young Jewess rejoicing in the name of Marcella Powers. ... " On the other hand, he is pleased to note that an editor, Richard Danielson, whose name aroused his suspicions, "is not a Jew."

To me, the most offensive references are to Mencken's pleasure at the exclusiveness of his club. Walking to the Maryland Club one day he hears from S. Blount Mason Jr., its secretary, the horrendous story of a man named Winter, a high official in a shipbuilding plant, who "seemed to be a presentable fellow," and was elected to the club. One day Winter entertained an elderly "and palpably Jewish gentleman in the dining room," who turned out to be his father. Mason investigated, found the member's true name was Winternitz. He was asked to resign, and did.

Mencken follows this narrative with another unlovely paragraph: "Mason told me there was no objection in the board of governors to bringing an occasional Jew to a meal in the club, but that this only applied to out-of-town Jews, not to local ones. There was a time when the club always had one Jewish member, but the last was Jacob Ulman. Ulman was married to a Christian woman, a great-granddaughter of Thomas Jefferson, and had little to do with the other Jews of Baltimore. When he died the board of governors decided that he should be the last of the Chosen on the club roll. There is no other Jew in Baltimore who seems suitable." The "Chosen" is one of Mencken's milder designations. He calls a well-known Baltimore businessman "a dreadful kike."

There is more of this ugly stuff in the book and apparently even more in the unprinted diaries. "The litany could go on," writes Charles A. Fecher, the editor, whose own sense of decency makes him admit "clearly and unequivocably: Mencken was an anti-Semite." The Post's critic denies this, claiming Mencken makes "exceptionally, generous appreciative comments ... about specific individuals who happen to be Jewish ... " It is true that Mencken never labels his publisher Alfred Knopf as a Jew or Walter Winchell, people who, it is only fair to note, were in a position to affect his career.

I must say this, reluctant as I am to characterize his recent defenders on this issue. (Some of my best friends are antisemites.) Generations later, in a climate that is still rife with threats and destructive acts against Jews and Jewish institutions, those who defend a writer such as H. L. Mencken must be said to possess an antisemitic sensibility themselves.

Doris Grumbach is a Washington writer.