Joni Mitchell is a counterweight to Grace Slick.  They both started out singing for what they thought was a revolution.  When they found out they were wrong, when the revolution melted down into disco, cocaine and "greed is good," they had to go on somehow.  Grace went on by letting the beautiful and wonderful Jefferson Airplane become "Starship," a mindless, schlock-rock money printing machine that fed her and some other people during the 80's.  Joni put on her walking sandals, shed a tear for all that was Woodstock, then put the revolution in her pocket and kept going.