"I wish they'd asked me to talk about something I know nothing about, like genetics," Walter Mosley says, only half-jokingly. The New York computer programmer turned best-selling crime novelist reckons he's drawn the short straw as far as the South Bank's "Sounding the Century" lecture series is concerned. Whereas Richard Dawkins, who will be speaking in March, can expound on something as simple as "man's place in the universe", Mosley - who could probably happily discourse on the Millennium microchip problem till doomsday - has been landed with the brow-furrowing subject of this century's race relations.
Still, it's a subject he is well qualified to talk about: born in Watts, the scene of explosive race riots in 1965 - his father, a survivor of red-neck Louisiana, his Jewish mother hailing from Eastern Europe - he grew up knowing that "if you're black in America, you are aware of it the whole time". He was trumpeted as Bill Clinton's favourite novelist on the campaign trail in 1992 - the president expressing his debt to Mosley's ruminative creation, detective "Easy" Rawlins, for showing "the way it was from a black person's view, particularly in the Forties, Fifties and Sixties". The success of the film of his first published novel, Devil in a Blue Dress, in which Rawlins moves between segregated white and black communities in 1940s LA, further ensured his becoming something of a spokesman for African-Americans.
So why is the lecture proving such a headache? The giveaway is that he has changed the title from "Since You've Been Gone" to "What's the Difference?" "I have problems with the notion that, if 10 years or 100 years go by, that's something special, or if 1,000 years go by, we should jump up and down," he explains. "When it comes to trying to figure out what's important about the turn of the Millennium as far as race relations are concerned, it's pretty hard. Ideas and circumstances may have changed, but people haven't. It's like asking what's the difference between 1200 and 1300 for serfs in central Europe: they probably wouldn't even know what day it is, just that it's raining." Downbeat Mosley's conclusions may be, but with a conversational reflex as lyrical as that, his lecture should, in the event, prove surprisingly inspirational.
Purcell Room, South Bank Centre, SE1 (0171-921 0600) 28 Jan, 7.30pm, pounds 6