In the immediate aftermath of the (Tucson shootings) crime, the “national conversation” focussed on the nation’s poisonous political and rhetorical climate. That conversation, which was worth having before, is not less worth having now because the connection between the crime and the climate is so murky — and it may well turn out to be more productive. If so, much of the credit will be due to Obama’s leadership. The atmosphere smelled cleaner in the days after Obama said what he said. Something had changed. No one can say how long the calm will endure. When it fades…perhaps the memory of it will leave us all in a better place.