He might take as a starting point the Greek philosophical opposition between mind and body and the establishment of a hierarchy, especially in Plato and his successors of the mind, as not only distinct from but superior to the body. This Platonic attitude toward the body informed much of Christian asceticism, in which sin (especially in Augustine) was rooted in our bodily nature. One could argue that this mind/body hierarchical distinction persisted through the Enlightenment.
Williams, as a Marxist, would note several things about this historical trajectory. The first is that philosophies which denigrate material goods can act as "opiates for the masses," distracting society from the material conditions of labor and of the working classes by treating material conditions as inherently trivial.
Another area Williams might look at is precisely the opposite of the Platonic, namely the valorization of the body in twenty-first century culture, something that also works as a means of oppression. The perfect models one sees in fashion magazines, both men and women, are emblems of an ideology in which people are supposed to cultivate their bodies almost as a moral duty; think of how people talk about being "good" as having to do with jogging or refraining from dessert rather than actually helping the poor or feeble. This distracts the working class from the conditions of their oppression. Also, money members of the working class spend on trying to look like members of the economic elite is money not invested in things that could enable them to improve their financial position, and thus the ideology of the cultivation of the body actually becomes a tool of class oppression.