Hurrah for Greenberg! His remarks about Nixon serve as a much needed reminder of both Nixon's shameful deeds and his unpardonable pardon, which Greenberg aptly characterizes as "one of the great triumphs of cynicism in American political history."
I agree completely that "to leave justice undone is to lower the moral tone of all society." Our moral tone is already low enough. Let's not forget Nixon--not because of mere vindictiveness, but as a way of ensuring vigilance and avoiding recurrence.