Look at the context of that sentence:
And yet, as Dr. King rose to take that pulpit, the future still seemed daunting. It wasn't clear what would come next for the movement that Dr. King led. It wasn't clear how we were going to reach the Promised Land. Because segregation was still rife; lynchings still a fact. Yes, the Supreme Court had ruled not only on the Montgomery buses, but also on Brown v. Board of Education. And yet that ruling was defied throughout the South -- by schools and by states; they ignored it with impunity. And here in the nation's capital, the federal government had yet to fully align itself with the laws on its books and the ideals of its founding.
So it's not hard for us, then, to imagine that moment. We can imagine folks coming to this church, happy about the boycott being over. We can also imagine them, though, coming here concerned about their future, sometimes second-guessing strategy, maybe fighting off some creeping doubts, perhaps despairing about whether the movement in which they had placed so many of their hopes -- a movement in which they believed so deeply -- could actually deliver on its promise.
So here we are, more than half a century later, once again facing the challenges of a new age. Here we are, once more marching toward an unknown future, what I call the Joshua generation to their Moses generation -- the great inheritors of progress paid for with sweat and blood, and sometimes life itself.
We've inherited the progress of unjust laws that are now overturned. We take for granted the progress of a ballot being available to anybody who wants to take the time to actually vote. We enjoy the fruits of prejudice and bigotry being lifted -- slowly, sometimes in fits and starts, but irrevocably -- from human hearts. It's that progress that made it possible for me to be here today; for the good people of this country to elect an African American the 44th President of the United States of America.
In this context, he's clearly calling on African-Americans to take advantage of the freedoms that Dr. King won for them.