GEM OF THE OCEAN Through Oct. 30, McCarter Theatre, Princeton, N.J., 609-258-ARTS, www.mccarter.org.

Overheard from the couple sitting behind me:

Wife (reading the program): It says that Aunt Esther is 285 years old. How can that be?

Husband: It's theater.

And that may be the best explanation of August Wilson's signature blend of realism and mysticism I've ever heard. Grounded in the gritty, detailed, authentic life of Pittsburgh, each of his plays has a liftoff where life transcends the mundane and the characters reach some magical, spiritual plane that transforms their existence. In Gem of the Ocean we watch a man, Citizen Barlow (Russell Hornsby) come to Aunt Esther (Phylicia Rashad) to have his "soul washed" because he is tormented by a dreadful deed. He undergoes a spectacular Jungian exorcism as he visits his racial past, finding himself, while in a Pittsburgh kitchen, chained to a slave ship during the infamous Middle Passage.

The kitchen is filled with richly developed characters who resonate with meaning beyond the personal. Caesar (Keith Randolph Smith -- the role director Ruben Santiago-Hudson played in the New York production) is the Bossman, with a badge and gun and a vicious streak of self-righteousness. His sister, Black Mary (Roslyn Ruff), works in Miss Esther's house and is clearly the heir to her mystical wisdom; Solly Two Kings (John Amos) helped 62 slaves escape and is struggling with the disappointment of the long-promised freedom. Everyone is both life-size and bigger than life, much like Michael Carnahan's realistic/surrealistic set, with its impossibly high staircase, immense windows and tilted door frame.

Gem is Wilson's next-to-last play (the newest, Radio Golf, has not yet been performed on the East Coast) and takes place in 1904, while slavery is still a living memory and while Lincoln's promises of freedom have not been sufficiently fulfilled. His characters suffer from various kinds of exploitation and are haunted by their own compromises, anger and guilt in an intense mixture of victimization and violence. It is to the credit of both the superb cast and Santiago-Hudson's direction that the emotionally charged script never descends into sentimental moralizing.

August Wilson's death several weeks ago at the age of 60 came after he had just completed his great project: to represent each decade of African-American life in the 20th century. The plays, in the chronological order of their content (not of their composition) are: 1900s: Gem of the Ocean; 1910s: Joe Turner's Come and Gone; 1920s: Ma Rainey's Black Bottom; 1930s: The Piano Lesson; 1940s: Seven Guitars; 1950s: Fences; 1960s: Two Trains Running; 1970s: Jitney; 1980s: King Hedley II; 1990s: Radio Golf. This dramatic chronicling was a massive undertaking, and that he finished the 10-play cycle is deeply gratifying.