WHEN nothing in your world seems to have much value, humor can carry you through. Like most Restoration comedy, William Wycherley's The Country Wife could hardly take a more cynical view of human nature. But the drama's light wit colors over the dark tone, and this Quincy House production keeps its audience laughing.

Under David Richman's direction the cast shows a generally good sense of timing. Their variation of voice and manner buoys up a long play that could easily fall flat.

All the characters are caught up in the delightful game of cuckoldry. The sophisticated ladies of the city are accomplished players, but the country wife. Mistress Margery Pinchwife, is grossly ignorant of the rulies.

Mistress Alithea (Sally Faith Dorfman) is the only one who does not what to join in the sport. She sincerely believes in fidelity, yet even she is not a completely positive figure. Her virtue appears ridiculous because her finance. Sparkish, to whom she is so stubbornly faithful, is the most absurd of the lot.

As Sparkish, Christopher Harding speaks in a falsetto and moves with a flourish which fully exploit the affectations of his role. He offers an excellent contrast to Pinchwife, played by Richard Minturn, who makes his face a sour, frowning mask that states his personality. Pinchwife is as overly protective of his wife's honor as Sparkish is negligent of Alithea's. Keeping his country wife under lock and key. Pinchwife confidently declares, "I understand the town." The audience takes enormous delight when the young, inexperienced Margery defeats the old coot, who thinks himself so wise.

Playing Mistress Margery, Susan Ehrlich has firm control of her part, though as the program notes inform us, she assumed it less than two weeks ago. She is completely convincing as the artless girl, unschooled in the ways of the city, but eager to learn.

Ironically, her lack of skill in the art of deception is nearly the undoing of Mr. Horner, the most accomplished fraud in the play. He makes love to all the ladies in town, after winning their husbands' trust by the false report that he is a eunuch. Michael Tratner shows ingenuity as well as confidence in the role. When three of his mistresses visit him at once, he casually juggles three oranges, handling the fruit and the ladies with the same case. Speaking almost entirely in double entendres, he uses the same words to say different things to different characters and, all the while, amuses himself and the audience.

The large cast sparkles in many of the smaller parts as well. Kenneth Demsky is particularly comic as Sir Jasper Fidget, who delights in mocking Horner, little suspecting that the supposed eunuch is making a fool and a cuckold of him.

The Country Wife is blatantly bawdy in a way that does not titillate the 20th century as it did the 17th. Restoration comedy has many elements that seem heavy now, but the Quincy House actors can keep more than just oranges in the air. Their efforts to juggle old-fashioned stage conventions are far from fruitless.