Comedy being viewed by the earthly literati more as a pourboir from the lesser gods than from the mightiest of Olympus, Neil Simon's "Chapter Two" last season did not get its deserved "best-play" Tony. It remains, however, the best from the writer of America's most successful, contemporary plays, and its opening last night at the Warner begins a six-week run which should be widely enjoyed.

Here Simon combines an intimate personal experience with his technical mastery to tell us about a writer whose beloved wife, Barbara, has died and who now marries a spunky, outspoken young actress. This is the actual background of Simon's marriage to actress Marsha Mason.

"Chapter Two," then, is a study about a condition in which most of the human race eventually participates. Grief stuns. But life, somehow, resumes, and in Simon's philosophy life is made bearable through laughter as a salve. George meets Jennie, who has just divorced Gus. George's brother, Leo, is having trouble with wife Marilyn and Jennie's friend Faye, bored with inattentive Sidney, considers a fling with Leo.

Simon's technical skill needs only four players, but scores of unseen characters, dominated by Barbara, populate his stage, actually two apartments designed by William Ritman, who includes two revolving circles to move us from room to room.

Simon's world has tightened over time through his ability to use a character's individuality for amusing dialogue. Long accused of being a trickster of the one-liner, vital to stand-up comics, Simon has honed his craft so that usually the laughs come through personal characteristics.

These facets would mean little if Simon were not astutely tuned to his audience. This is the broad middle class of America, and almost anything Simon mentions is familiar to this relatively prosperous, mobile segment: macadamia nuts, extra-strength Tylenol, airline food, lines from old movies ("My regiment was just called up"), horoscopes, hummed snatches of popular songs, psychoanalysis and specific cities ("I'm going to Cleveland for a couple of days or a couple of weeks." "In Cleveland a couple of days are a couple of weeks.")

In Simon's world, women are usually superior, certainly more intelligent than men. How did those patient, unseen wives of "The Odd Couple" ever come to marry such oafs? It is the male who collapses under the urban strains of "The Prisoner of Second Avenue."

In "Chapter Two" it is Jennie who cries: "Everyone out there's looking for easy answers... Maybe... You'd be just as surprised as me at some of the maybes I've seen out there lately... We'll, nonehat is for me, George. You want me, then fight for me because I'm fighting for you... I think we're both worth it."

Jennie's friend Faye is a comedy contrast, but she's as basically sane as Jennie. She remains faithful to Sidney. Leo surely is related to the Leo of "The Odd Couple" and George, for all his widower's woes, is just a grown boy who needs pampering. Women in Simon's audiences are aware they are preferred, quicker, more sensitive, less selfish.

Though the telephone's decades have made possible all sorts of one-character and two-character "plays," no dramatist uses this panacea of the middle classes so deftly as Simon. His best phone scene is the introduction of George, who thinks he's calling an 85-year-old woman, to Jennie, as amused as Shakespeare's Katharine when Henry V attempts to captivate her with his fractured French. Simon even finds a way to get a laugh from the icy silence of a mechanical answering device.

This company is new to the play, having opened 10 performances ago in Atlanta. The start was heavy last night but Jerry Orbach's first phone scene as George with Marilyn Redfield's Jennie picked things up smartly and they make the couple wholly credible. Jane A. Johnston is an adept comedienne as Faye and the immediately identifiable Herbert Edelman (of the TV commercials) as Leo will be far more amusing, even touching, when he stops making with the hands on every speech.