Nunnally Johnson, who died in 1977 in his 80th year, was one of the most successful screenwriters ever to toil in Hollywood; over three decades his credits ranged from "The Grapes of Wrath" to "The Desert Fox" to "Mr. Hobbs Takes a Vacation." He was also living proof that it really is possible to live and work in Hollywood and still be a person of wit, erudition and civility.

He knew just about everybody, not merely in the movies but also in journalism, show business and politics. Though he worked in a town that lived and died by the telephone, he was an old-fashioned sort who loved to write to his friends and who did so exceptionally well. The result, thanks to the labors of his widow, Dorris Johnson, and Ellen Leventhal, is this slender but thoroughly engaging collection, which will be published at the end of the month. As Alistair Cooke observes in his foreword:

" . . . beyond the record of a gifted man's joys, troubles, escapades and affections, what this has turned into also is an insider's diary of the fun, the guile, the allegiances and enmities, the social habits and pretensions of the movie colony for 30 years or more in the middle of the 20th century."

It is not a book that invites sober analysis, but one that delights and surprises.

There is, for example, this story told to Johnson by the suave George Sanders, who was estranged from his wife Zsa Zsa Gabor, who was in turn having an affair with Porfirio Rubirosa. Determined to get the goods on her, Johnson writes in 1954, Sanders and "four Sam Spades" broke into her bedroom:

"So he dashed in bravely and found himself in a scramble with a Venetian blind. Through them he saw two naked forms break the record for the dash to the bathroom, where the light was on. As soon as he could untangle himself from the blinds, George rallied at the head of his operatives and all made a dash for the privileged sanctuary. Rubi and Zsa Zsa had slammed the door shut but in their excitement they forgot that it could also be locked. The door opened inward and then it became a head-on push between George and Rubi, Rubi trying to hold the door shut, George trying to bull it open . . . "

Johnson, who was a country boy from Georgia, enjoyed the antics of the movie folk yet always kept a certain distance from them. He was great friends with Humphrey Bogart and Lauren Bacall, for example, yet he saw them with a clear eye:

"We will set out for the revels with the Bogarts, which may complicate matters still further. Betty would go to parties three times a day if they were available. She has an appalling energy. Tonight, I'm sure, she will see herself as the Toast of New Orleans and I will be carrying the roses that she will clutch between her teeth. Bogey of course will be busy working on his own legend as Quite a Character, setting fire to people, et cetera. Don't you wish you were here?"

Johnson was an amused and relatively dispassionate observer of Hollywood and its rituals -- "the company-town atmosphere, the gossip, the trade papers, the rumors, the eternal luncheons with the same people, the politics in the studio, all that stuff" -- but he was also a professional who took his work seriously and accomplished it efficiently. Because "the writing of a script is often a pretty disorderly business," he preferred to be his own producer as well as writer, which he was able to do once he had made his reputation. Eventually he added directing to his repertoire, with "The Three Faces of Eve" being his greatest success.

That picture starred the young and then-unknown actress Joanne Woodward, in whom Johnson quickly recognized a fellow professional: "When she came to the set she was prepared. It happens occasionally that an actor or actress makes all these preparations and comes to the set equally prepared, but prepared for what seems to me the wrong conception. Joanne's seemed to me right. She rarely asked even for advice. She simply rehearsed it and looked at me to see if I thought it looked okay. It nearly always did. This is the kind of acting that makes a director look very good indeed."

Reflections such as this upon the craft of the movies are frequent in "The Letters of Nunnally Johnson," but the book's greatest attraction is the steady current of humor and irreverence that runs through it. In a letter to Clifton Fadiman, for example, Johnson elaborates upon "the Circumstantial Pun, which calls for a very special and often highly complex set of circumstances for its use." A case in point:

"Suppose . . . that Syngman Rhee had a son who came to this country and obtained employment with one of the Luce magazines. Suppose, then, too, that he disappeared mysteriously and a citywide search was instituted for him. Then in the course of time he would have to be discovered, perhaps in a Third Avenue saloon. Then the detective could walk up to him and say, 'Ah, sweet Mr. Rhee of Life, at last I've found thee!' "

Quoting these letters is addictive; so is reading them. From start to finish they are funny, perceptive and intelligent. Imagine what a joy it must have been to receive them.