In addition to singing "Amazing Grace"—with the surprised people on the dais, the choir, and the whole crowd then joining in with him—Obama spoke about history:

Reverend Pinckney once said, "Across the South, we have a deep appreciation of history — we haven't always had a deep appreciation of each other's history." (Applause.) What is true in the South is true for America. Clem understood that justice grows out of recognition of ourselves in each other. That my liberty depends on you being free, too. (Applause.) That history can't be a sword to justify injustice, or a shield against progress, but must be a manual for how to avoid repeating the mistakes of the past — how to break the cycle. A roadway toward a better world. He knew that the path of grace involves an open mind — but, more importantly, an open heart.

That's what I've felt this week—an open heart. That, more than any particular policy or analysis, is what's called upon right now, I think—what a friend of mine, the writer Marilyn Robinson, calls "that reservoir of goodness, beyond, and of another kind, that we are able to do each other in the ordinary cause of things."

That reservoir of goodness. If we can find that grace, anything is possible. (Applause.) If we can tap that grace, everything can change. (Applause.)

Amazing grace. Amazing grace.

You can watch the whole eulogy here.