I know that Bush, for political reasons, is going to nominate a minority, a Hispanic man or someone where it will be harder for people on the progressive side to oppose and split some of the traditionally progressive or democratic constituents.
I think one of the reasons people quit is because they're afraid they won't be able to get better and better; that they have to come to a zenith of some kind.
I vividly remember the summer of 1964 with its voter registration drives, boiling racial tensions, and the erupting awareness of the cruelty of racism. I was never the same after that summer.

