ONCE UPON A TIME, back in the days before illustrated weeklies featured articles on cohabitation of relationship-ers, love was a monosyllabic thing. Ah woe! But even then it could be complicated.

Imagine Casilda, the beautiful daughter of a pompous but penniless 18th century Spanish grandee, who was not just plighted or promised but irrevocably linked for life, by proxy at birth (unbeknownst to herself) to the since-abducted infant heir to the throne of Barataria. That's bad. And to add to the confusion: the infant heir is supposed to have grown up in innocent obscurity to be a Venetian gondolier, or rather, one of two Venetian gondoliers, brothers, who have--rather awkwardly--recently married. Only one person can truly identify the next King of Barataria: that is Inez, coincidentally the mother of the grandee's solo retainer, Luiz, a lowly but virtuous drummer boy who is carrying on a secret but virtuous affair with Casilda. Although not exactly Newsweek cover story material, this complicated nonsense is just right for part of the plot of Gilbert and Sullivan's operetta The Gondoliers now playing at the Agassiz Theater.

The competent production (under Robert Atkins' supervision and John Lundeen's direction) has a peppy script, decent choreography and show-stealing sets and costumes. No Venice could be imagined more beautifully than the set designed by John Magoun and painted by Marj Ingalls Beaty. It's a marvel of oceanic expanse on a swimming pool-sized stage. Although familiar as a National Geographic photo, the set shimmers with fairy tale color, its magic undiminished by the costumes designed by Linda Beyer and Gail Simonson. From the nobility's full regalia to the page boys' gray bibs, every outfit sparkles--jeweled or not.

But scenery flats and starched aprons cannot mug for the audience or recite witty lines. Scenic and vocal delights pale when the direction is drab and comic potential ignored. Although the company's voices are strong and clear, they may as well be disembodied. The staging is sometimes pedestrian, and there is a peculiar reluctance to ham up the show.

Part of the problem may have been prompted by the script itself. The gondoliers are fervent believers in republican principles of equality. But that does not mean that their friends in the chorus, when dressed alike, have to act alike too. Shipley J. Munson and Jane Gitschier are consistent exceptions--the former by his air of zany snootiness, the latter by her charming joie de vivre.

The leads could also have been misguided by the composition of the play. Gondoliers was written to have no shining stars (Gilbert created seventeen leads in a fit of pique that members of D'Oyly Carte Opera Co. had just won large pay raises.) At least on stage, lovers tend to display stalwart sincerity--such unchanging goodness making them a bit dull. operetta has not just one cooing couple but three. It does not have to be so monotonous: only Luiz and Casilda (ably played by Willy Falk and Linda Cameron) need stand out as the sincere romantic leads. Faced with the prospect of renouncing principles for great wealth and wives for gorgeous Casilda, the two gondoliers (Stephen Montgomery and Howard M. Cohen) could have been a little more greedy, a little more torn, a little more befuddled in their predicament. Instead, under Lundeen's direction, they are merely predictable--in stereo.

The gondoliers' wives (Katherine Kean and Mary Jane Robbins) have more comic personalities. Their physical appearances cor trasting well, the two have the luck to wear with elan honeymoon negligees that would--well, that would never be seen on the body of a Cosmo Girl.

Jefferson Vander Wolk plays the Grand Inquisitor, a Machiavellian type who kidnapped the prince to prevent the spread of Wesleyanism, with less character. Vander Wolk's voice is strong, but for a powerbroker his appearance is rather wraith-like until he trips awkwardly into songs.

The grandee and his wife, known as the Duke and Duchess of Plaza-Toro, initially appear two dimensional but that's because they float across stage on a gondola bearing a resemblance of sorts to Washington Crossing the Delaware. But nothing is flat about David S. Brown's and Diane Nabatoff's performances. Nabatoff manages to look both pinched and bombastic simultaneously. Uppercrustedly on the bourgeois make, Brown has the perfect Hogarthian face for the role: his oblivious facial reactions to his own spectacular antics make him all the funnier. With Brown as the Duke of Plaza-Toro, it is the couple that caws together that brings life to the stage together.

These comments that The Gondoliers seems static and low key are not intended to be harsh. I had to attend the Sunday matinee performance at which half the audience was either over seventy or under ten. They are not particularly responsive age groups: one not prone to belly laughs, the other a little slow on puns. But even septegenarians, kindergardenians and stray matinee-goers--in the words of W.S. Gilbert himself--beg, desire, demand a show with gusto. Still, this production of The Gondoliers is enjoyable. On bad days, it is at least beautiful pictures set to well-performed music. On good ones, it might truly sparkle. And that's more fun than illustrated weeklies any time.