Value to Society

"Also implicit in the I.Q. controversy is the notion that mental tests are not only intellectually invalid, but morally 'unfair' if they do not measure 'real' or innate ability. But there is no more individual merit in having received a windfall gain in the form of brain cells rather than in the form of encyclopedias or private schooling. Each individual is born into a world he never made, with a brain he never made. His moral claims are no greater or less, whether heredity or other circumstances beyond his control gave him his advantages or disadvantages. Similarly, his value to society is the same, whether that value originated inside his head, or inside his home or school, or among his companions."

-- Thomas Sowell, The Economics and Politics of Race, p. 145

I'm curious about the meaning of "his value to society." My curiousity is not specifically with respect to Sowell's point in this paragraph. I think this phrase has a more general use than just in the discussion of I.Q. What do you think this phrase means?