that illusion is essential, and it cannot persist without at least a measure of reality. Just how much reality there is in this appearance of upward and downward mobility varies and is subject to learned dispute, but there can be no reasonable doubt that it does have a good deal of reality: when the system of roles itself is changing so much, the occupants of positions within it cannot be, as some leftwing sociologists claim, tied to a rigid stratificational system. Compared with agrarian society, this society is mobile and egalitarian.