Why does Morrison write that the slavebody has not completely left the American psyche?

Morrison writes that the slavebody -- the idea of the black person in America being 'ownable' and subservient -- has not completely left the American psyche because it is now found embedded in the concept of the blackbody. The blackbody is used by her to signify the post-slavery black American who is not 'ownable' and who is free, yet she highlights the way that black as a skin color is the common denominator between the slavebody and the blackbody and also is the key difference between these two concepts and that of the white person. Thus, both are made out to be the 'other,' and in fact the blackbody's black skin color links it inextricably in the mind of white American ruling classes as a continuation of that which was once 'ownable'...