It will be hard to get off the mobility theme. In a NY Times book review (Feb 1) University of Texas economist James K. Galbraith begins with a factoid from Perfectly Legal: The Covert Campaign to Rig Our Tax System to Benefit the Super Rich -- and Cheat Everyone Else, by David Cay Johnston: "... from 1970 to 2000 the income share of just 13,400 households, the richest hundredth of 1 percent -- rose from 1 percent to 5 percent of all income, and from 100 to 560 times the national average ..." We know that the membership of this cohort was not the same in 2000 as it was in 1970. I expect that Prof. Galbraith knows this too. Why not add this caveat? And, would that fact change his outrage and mute his point? Omissions of the mobility story are the norm. Yes,there are axes to grind but how about some respect for the effects of social mobility? Maybe it makes a bigger point than the cited quote.