STRATFORD, Conn.--One of the tasks of the theater is to reassess the works of our playwrights a decade or two after their original productions. As part of its 20th season, the American Shakespeare Theater is fulfilling this function by turning for the first time in its history to a play by a living American dramatist.

It seemed appropriate to someone to select a work dating from 1955, the year the AST opened. The choice fell on Cat on a Hot Tin Roof by Tennessee Williams, who is, along with Arthur Miller, generally considered one of the two foremost native dramatists of our time.

As it happened, both Williams and Miller faced Broadway audiences that year, the latter with A View From the Bridge. Coincidentally, both plays were revised by their authors, both showed the influence of ancient Greek drama, both dealt substantially with homosexuality, and both were on this account denied a license of London production by the Lord Chamberlain.

Homosexuality was then hardly a new subject for the stage. After all, Edward II, by Shakespeare's contemporary Christopher Marlowe, is a masterly drama about a homosexual kind of England. In our own century, Broadway audiences were confronted with the topic during the twenties and thirties through such plays as The Captive, The Pleasure Man (by Mae West--who, we tend to forget, wrote as well as acted), The Children's Hour, The Green Bay Tree and, later, Tea and Sympathy. Prior to Cat on a Hot Tin Roof, Williams himself had invoked the subject tangentially in A Streetcar Named Desire, and would return to it more seriously three years later in Suddenly Last Summer.

But theater audiences have notoriously short memories. When Cat was first mounted, Williams was widely deemed a purveyor of sex, sensationalism and violence; the play was found shocking, with most of the talk focussed on homosexuality and the inclusion of a bawdy joke about an elephant's erection.

Today, after a decade that has brought us such outspoken dramas as The Toilet, The Killing of Sister George, A Song at Twilight, Fortune and Men's Eyes, Staircase, The Boys in the Band, and, just this spring, Find Your Way Home, homosexuality is no longer shocking and virtually anything is grist for stage treatment.

This opening up has the advantage of allowing us to go back to a work like Cat with a balanced perspective. Sure, homosexuality is a factor in the play; but we can now more easily appreciate that it is not the central subject. Only last year, shortly after publicly acknowledging his own homosexuality, Williams stated, "I have never found the subject of homosexuality a satisfactory theme for a full-length play."

Cat, like most of Williams's plays, casts its net far wider, exploring a number of major themes: illusion and reality and the impact idealism has on them (there is a lesson in the fact that, in this matter, Williams and O'Neill--in The Iceman Cometh--could take opposing positions and both be convincing); the need to overcome isolation and the obstacles to communication and worthy personal relationships; the nature of power, both materialistic and spiritual; and sexual conflict and guilt (heterosexual as well as homosexual). As often with Williams, disease and neurosis and death are also involved--and so is humor.

The earlier Glass Menagerie and Streetcar remain his finest achievements. But Cat ranks next, and had no trouble making a strong initial impact. It copped the Drama Critics Circle Award and a Pulitzer Prize, not to mention an unexpected accolade from Fidel Castro. It is sad that, in the ensuing two decades, Williams has, for all his activity, not produced another first-rate work, and we have had only a series of rehashings and fitful flickerings. But nothing can detract from the luster of his early masterpieces.

Cat plunges us into a predatory Southern family not unlike the Hubbard household so splendidly limned by Lillian Hellman in Another Part of the Forest and The Little Foxes. At the head is Big Daddy Pollitt, who has amassed a fortune of nearly $10-million, never stops bragging about his "28,000 acres of the richest land this side of the valley Nile," and is unaware he has terminal cancer. He loathes his wife, Big Mama, with whom his sex life has been no doublebed of roses.

Big Daddy's elder son, Gooper, is a greedy lawyer slavering to inherit the estate, and is married to Mae, a snotty and equally money-minded mother of an ever-expanding obnoxious brood of "no-neck monsters." The younger son, Brick, is an ex-athlete fallen into alcoholism, who refuses to become involved with anyone, including his wife Maggie. She is thus not only sexually frustrated and childless but, born into poverty, also fearful of losing the wealth into which she married. On the sidelines is the Reverend Tooker, a local clergyman adept at sniffing a fat bequest for a church memorial.

These are not your ordinary next-door neighbors. Williams has made them larger-than-life, like the characters in ancient Greek drama, and has tried, in his words, to portray the "fiercely charged interplay of live human beings in the thundercloud of a common crisis." Furthermore, despite the play's three acts the action is absolutely continuous, being confined to two and a half hours on the evening of Big Daddy's 65th birthday. Not only does the work satisfy Aristotle's suggestions but it also meticulously observes the three unities, of time, place and action so dear to the hearts of Renaissance theorists.

Although the cast contains some fifteen players, the core of the play--again as in Greek drama--lies in big duologues separated by choral passages (sometimes literal offstage singing). The first act, like the others, takes place in the combination bed-sitting-room occupied by Maggie and Brick, and it belongs almost exclusively to them. In fact, we have here not so much a duologue as a monologue by Maggie, for she talks more at him than with him. Brick, whose tippling has resulted in a broken leg, is always physically present, with crutch and cast, but his mind is almost always elsewhere. Maggie's babbling and bitching merely bounce off her boozer.

In the second act, the galvanic Big Daddy won't tolerate Brick's detachment. The two of them, alone on stage, have a knock-down drag-out dispute in the tradition of the Greek agon. This is the most powerful scene in the play, and one of the most powerful in modern drama. Williams is often at his most effective when he is autobiographical. Tom and Laura in Menagerie were modeled on the playwright and his introverted sister Rose, who had to be institutionalized for life. The confrontation in Cat was his way of trying to exorcise the demonic memory of his taunting and bullying father--much as O'Neill did in a still greater play, Long Day's Journey Into Night.

Here, with persistent and painful probing, Big Daddy pries out of Brick a reason for his refuge in alcohol: disgust at the world's hypocrisy--or "mendacity," as Brick puts it. Part of this disgust is self-disgust at the outcome of Brick's "pure and true" friendship with his now-dead football pal Skipper, a relationship that was homosexual on one side and, at least latently, on the other. Forced to face truth, Brick turns the tables and reveals that what Big Daddy thinks is a spastic colon is actually a metastasizing malignancy.