Ten years ago, the Broadway theater was, on the whole, foolish, overblown, overpriced and (to judge from the declining number of plays and functioning auditoriums) headed for financial oblivion. Today Broadway is more foolish, more overblown and more overpriced than ever -- and enjoying a mysterious wave of prosperity.

Who can explain it? Who can tell you why?

Fools give you reasons. Wise men never try.

The experts will, if pressed, cite the cleanup of Times Square and such marketing innovations as the use of credit cards and telphone charges. Privately, no one is very sure how to explain this resurgence. Privately, no one fully believes it.

And well might one not. When Broadway went into its tailspin in the '60s, it was still the site of the best, the most polished and the most stimulating theater in America. Today, most of its substantial plays come from elsewhere, while the frivolous home-grown product -- inflated cabaret shows, lumbering revivals and nostalgic drivel, at $15 to $30 a ticket -- is a shabby return on anyone's entertainment dollar.

And what does the future hold? According to Price Berkley's "Theatrical Index" -- that invaluable periodical that Broadway producers consult whenever they have a dumb idea and want to know if some other producer has had it first -- we can look forward to these breathtaking possibilities:

New musicals based on "Dennis the Menace," "Jack the Ripper" and "The Hunchback of Notre Dame"(to be called "Quasimodo"); a musical updating of "Bye Bye Birdie" called "Bring Back Birdie"; a play called "The Boys of Autumn," about Tom Sawyer and Huckleberry Finn and adults; an X-rated extravaganza called "Playboy on Broadway" to honor the magazine's 25th anniversary; and revivals of "The Music Man," "camelot," with Richard Burton, and "My Fair Lady" with 71-year-old Rex Harrison as Higgins and 90-some-year-old Cathleen Nesbitt as his mother. (Julie Andrews has been adjudged too long in the tooth to repeat her roles in these musicals).

By contrast, the current roster of shows looks downright daring. But perhaps the play is no longer the thing. Perhaps the Broadway theater should be reviewed as a living museum and patronized (if at all) for its architecture, atmosphere and ritual rather than the quality of the product it dispenses.

For those who insist, nevertheless, on knowing what they're seeing, here are four current choices:

The desperation of the nostalgia binge is underscored by the acclaim for "Morning's at Seven," a forgotten 1939 comedy by a forgotten playwright, Paul Osborn. Set in the backyards and on the rear porches of two middle-class, midwestern homes, "Morning's at Seven" is a whimsical, low-keyed chronicle of small traumas in the lives of four elderly sisters.

The play turns on whether Homer, the shy 40-ish son of Ida and Carl, will finally marry Myrtle, to whom he has been engaged for 12 years or so.He has just brought her home to mom for the first time -- which everyone regards as a good omen. But when his slightly loony old man starts having one of his "dentist spells" (asking himself why he never became a dentist) and then, worse, one of his "Where am I?" spells, Homer decides he can't leave his mother alone to deal with such crises.

Osborn has some of Thornton Wilder's sensitivity to the comical shadings of small-town life, and for a while he makes these minuscule matters entertaining and affecting -- which is a large feat. In addition, without parading his interest in the problems of the elderly the way today's playwrights do, he casts a gentle light on the unwritten agreements and unexpressed apprehensions of people in their 60s and 70s.

Physically, the production is stunning -- with real trees, convincing grass and four national landmarks in the persons of Teresa Wright, Maureen O'Sulivan, Elizabeth Wilson and Nancy Marchand as the sisters. (Marchand, by the way, is vague and frazzled and could not be more different from the chic newspaper magnate she plays on TV's "Lou Grant.") But as the play develops, its tone veers awkwardly between realism and whimsy, and heads for a contrived resolution that considerably diminishes what has come before.

"Johnny on a Spot," at the Brooklyn Academy of Music, is another play brought back from the dead. Charles MacArthur -- writing, for once, without collaborator Ben Hecht -- composed this upside-down version of "The Front Page" in 1941. The heroes are machine politicians, and the villains are newspapermen. The title character is the incumbent governor of a nameless southern state who has to circumnavigate a series of obstacles in his path to the U.S. Senate, the most formidable being his death -- on election-eve in the town brothel. The rest of the play concerns the efforts of Johnny's loyal supporters to conceal his death, get him elected posthumously, and, by smuggling his body back to the governor's office, prepare him for a more dignified demise at his desk.

"Johnny" telegraphs some of its moves, and its anarchy isn't always as adroit as it ought to be, but like "Morning's at Seven," this is an impressive production that reopens an abandoned vein in American playwriting. The members of the BAM company fill "Johnny's" 40 roles splendidly, and the play abounds with mad moments. At one point, needing the deceased governor's signature, his campaign manager summons a convicted forger from the state penitentiary and fills his head with dreams of an early parole. But when the assignment has been explained to him, the forger is aghast. "You mean," he asks incredulously, "you want me to commit forgery?"

Mark Medoff's "Children of a Lesser God" (scheduled to come to the National Theatre next spring) hails from Los Angeles' Mark Taper Forum. It is about the relationship between a militant deaf woman (played by Phyllis Frelich, a deaf actress) and the unusually determined teacher who becomes her husband (played by John Rubinstein). He wants to teach her to speak and lip-read. She wants neither skill. "I don't do things I can't do well," she explains. s

"Are you afraid," Rubinstein asks, "that if you begin to show people you're enjoying life in the hearing world, they'll revoke your license as an angry deaf person?"

Ironically, her militancy makes her more reliant on others, since without the ability to lip-read she has to use her husband as a secretary and interpreter. In one scene, seeking relief from such duties, Rubinstein tries to lose himself in a recording of Bach. But it doesn't work. "I can't enjoy my music because you can't," says the actor, who happens to be the son of pianist Arthur Rubinstein. Then he tries to explain, in sign-language what music is.

Frelich uses sign-language exclusively, while Rubinstein translates her words, and his own, into spoken English. This takes some getting used to, but it can be gotten used to -- thanks largely to Rubinstein's valiant work in an extraordinary role. "Children" is slow at times, and the staging (by Gordon Davidson) is decidedly unsubtle, but these may be necessary concessions to the task of satisfying deaf and hearing audiences at the same time, which is probably the play's most remarkable achievement.

Neil Simon's latest comedy, "I ought to Be in Pictures," is one of his more controlled and satisfying efforts, with an almost bearable minimum of food jokes, East Coast-West Coast jokes and the other Simon standards. Better still, Ron Liebman (of "Norma Rae" and "Kaz") gives a terrific performance as a down-on-his-luck Hollywood screenwriter visited, one morning, by the daughter he hasn't seen in 16 years.

Dinah Manoff (in real life, the daughter of actress Lee Grant) is a splendid foil for Liebman, and her tough New York teen-age act brings out a new, less testy, more befuddled side to Liebman's personality.

These two make much of "I Ought to Be in Pictures" a pleasure. But the play itself seems disorganized. It could easily end with the first act curtain, and the daughter's interest in an acting career -- a major plot point -- evaporates with unaccountable suddenness.

Liebman and Manoff have, besides plenty of talent, good, strong voices -- making it an absolute mystery why producer Emanuel Azenberg and director Herbert Ross have chosen to amplify this show, robbing Liebman's performance, in particular, of much of its subtlety. For that crime, they should be sentenced to life imprisonment in the bowels of a Moog Synthesizer.