Oscar Brown Jr. is a modern griot--a storyteller who uses myth, rhyme, and rhythm to impart wisdom. His exultant tone poems and narratives, which he's been creating for more than 30 years, are important precursors to rap. But unlike many rappers he spins his tales with affection and irony--he's never ceased to "take time and make it swing," and he still manages to find "gold in the ghetto." "Dat Dere" is a hilarious, affectionate portrait of an inquisitive youngster badgering his father for answers; Brown's take on Mongo Santamaria's "Afro Blue" is a hauntingly beautiful meditation on the strength and glory of the African-American cultural tradition. But don't expect a night of mere jollity; Brown doesn't temper his message. His lyrics to Scott Joplin's "The Entertainer," for example, tell the bitter tale of a "talented son of a slave" whose art was appropriated by the white overclass and who died without reaping his just rewards. Brown is probably best known in Chicago for Great Nitty Gritty, the "urban-contemporary" musical he mounted here more than a decade ago, but to those of us who've followed his solo act for years, it's clear that's where his true artistry shines. Friday and Saturday, 8:30 and 11 PM, Spices Jazz Bar, 812 N. Franklin; 664-6222.