If Rosalind, the intrepid heroine of William Shakespeare's As You Like It, were a character in a modern novel, we'd demand that the author furnish some pop psychology to explain what makes her tick. Did she have strong role models as a child? Did her parents encourage her independence? Did she go out for Little League?

But Shakespeare is Shakespeare, and so As You Like It gives us Rosalind full-blown - brave, intelligent, so eager to embrace life and all its marvels that she falls in love like a shot.

Such a Rosalind is Suzanne O'Donnell's in the Orlando Shakespeare Festival's production of As You Like It.

Small and impish, with a head full of tousled brown curls, O'Donnell's is a Rosalind to adore, and her down-to-earth wisdom rightly takes the foreground in this sublimely wise play.

Directed by Russell Treyz, this As You Like It uses no flashy gimmicks to spice up one of Shakespeare's most cerebral tales. As such, it's a mild-mannered, well-considered production - thoughtful, not always entirely inviting, but sparked by performances that bring the show to life.

As You Like It is called one of the greatest of Shakespeare's comedies partly because it's not an easy play.

Not a lot happens except at the very beginning and the very end; the characters mostly wander around the Forest of Arden and talk.

That the plot is littered with brothers who are warring with brothers and with fathers who are separated from their children is less important than the philosophies of all those estranged characters. Nearly all of them, in one way or another, have left moderation far behind.

What those characters learn in the ultimately magical Forest of Arden, in fact, is how to embrace moderation. What they learn, in essence, is how to love.

That's true for brothers Oliver and Orlando, who learn to put their feud behind them; it's true for the jester Touchstone, who lays aside his sophistication and takes up an earthy wife.

It's true, especially, for the lovers Orlando and Rosalind, who discard his lovesick prattling and her childish playacting for a more mature and balanced love.

Designer Kelly Ryner has created a stark contrast between the cosmopolitan court of Act I and the later, wilder environment of Arden: Ivory panels fill the spaces between the set's bleached gray wood columns at court, and they reverse to show the lush, dark trees of the forest for the rest of the play.

Michael Reese's soft pink and blue lighting at court turns to warmer tones for the forest, and Sandria Reese's cream-colored court costumes give way to others in darker, woodsier hues.

It's in the forest that this show comes to life, where one besotted character stumbles over another equally so and where the most urbane of courtiers - clownish Touchstone and gloomy Jaques - find themselves enough out of their element to voice their most pungent thoughts. At court, Treyz's production is earnest, well-spoken; in the forest, its performances spring forth.

Many of them do so vividly - Karen White as Rosalind's warmly loyal cousin Celia; Paul C. Vogt as the insipidly lovelorn shepherd Silvius; Max Jacobs as Rosalind's father, the sweet-tempered Duke Senior (and as his crazed usurper, Duke Frederick); William Preston as Orlando's servant, the frail and faithful Adam; and, in a tiny role, Steven P. Lewis (the Puck of last year's festival) as the dimwitted but sensible shepherd Corin.

Rainard Rachele makes Jaques a man of great intelligence who simply can't abandon his head for his heart, and he makes a lovely thing of the monologue that begins, ''All the world's a stage . . .'' And Paul J. Kiernan runs riot with the acerbic Touchstone, whose aversion to the country is such that he chokes on a blade of grass; Kiernan ad-libs like crazy, and the audience eats it up.

Yet in this production, it's the young lovers who work most of the play's charms. Jim Helsinger - a wonderful Antipholus in the festival's Comedy of Errors - is equally so as the lovesick Orlando. This youth is headstrong enough to be called ''the stubbornest young fellow of France,'' but that force of character comes across, too, in more sympathetic ways: in an innate good cheer, in a trueheartedness toward Rosalind that's lovely to behold.

Put him beside O'Donnell's Rosalind, and the two overcome any excessive mildness this production may have.

Treyz finds in the two actors a playfulness and a profundity that make each the other's match. It's no accident that playfulness and profundity are what As You Like It is about.