Coverage of the memorial service held for Reverend Clementa Pinckney in Charleston last week focused largely on the surprising moment when the leader of the free world broke into song. That song, of course, was “Amazing Grace” and the president sang it distinctly in the style of the black church.

For all the attention Obama’s unexpected performance received, though, it’s worth taking another look at the “Amazing Grace” clip, this time watching for the silence. His singing seems to be a release of the collective tension that had been building for a week after the Emanuel A.M.E. shooting. But the preceding pause seems to hold its hearers captive. Though he is frequently interrupted with cheers and amens throughout his eulogy for Reverend Pinckney, the pause he takes 35 minutes into the speech is easily the longest break from the text before him.

Between the second time he speaks the words “Amazing Grace” and the first time he sings them, 13 full seconds pass. Thirteen seconds with thousands hanging on his next words: grieving church members, a phalanx of purple-robed clergy, and a church band that had until then had been all too ready to accompany him with organ trills and guitar licks.

During those 13 seconds, Obama looks out over the crowd, then down at his notes, then he shakes his head slightly. Watch behind him; the assembled clergy seem momentarily unsure what will happen next. They sit still, watching him. The only movement comes from Bishop Julius H. McAllister, seated just to the left, who closes his eyes and sways as if he can already hear the music. Throughout the eulogy, the president’s words had been met with call-and-response encouragements, but for every one of those thirteen seconds there is only silence.  

Obviously, Obama knows how to work a crowd. He’s familiar with the rhythms of worship in the black church; he usually rides them effortlessly. But this long pause was different. What did it mean?

“Silence is to sermons what space is to magazines,” Mark Galli, a former pastor and current editor of the evangelical magazine Christianity Today, has written. “If an article simply begins in the upper left-hand corner of a page (or fails to use columns or uses all of the page for words), we’re less likely to read it.” White space not only provides a frame; if used well, it also focuses attention, raises expectations, and heightens the encounter with plain text on a page. An unexpectedly quiet moment in the midst of intense preaching attempts to do the same. As Richard L. Eslinger, another evangelical writer, put it, “Without a necessary silence, the power of words decays.”

“Some preachers use a pause at the beginning of a sermon to establish mutual ‘presence’” with their congregations, the Lutheran-minister-turned-Catholic-priest Richard John Neuhaus once wrote. “Similarly, a brief pause in the middle of the sermon or at some other point along the way can effectively reestablish presence and purpose.”

This was a homiletic gambit particularly favored by Martin Luther King Jr. When called to the pulpit, Neuhaus remembered, King would often stand and wait “sometimes ten seconds or morebut it would be “a very active kind of waiting,” in which he would look out over the congregation, “establishing his identity to them, and theirs to him.” And in those accumulating seconds, it would become clear “something important was about to happen.”

Silence isn’t necessarily associated with black churches in the popular imagination. The notion of religious silence may evoke thoughts of Trappists using monastic sign language to avoid disturbing the contemplative calm of the cloister, or a meetinghouse full of Quakers patiently listening to the clock tick until someone has something to say.     

Yet long pauses like the one Obama used in Charleston are an overlooked part of worship in many black churches. In his 1995 book, The Hum: Call and Response in African American Preaching, Evans Crawford suggested that silencewhat he called the “sermon pause”often becomes a third partner to the familiar pairing of the preacher’s questions and the congregation’s affirmative replies.

“It is not a ‘dead silence’ but a ‘live silence,’” Crawford writes. “It is a silence that organizes time, that invites us to think of time not as something passed but as something plotted.”

In the introduction to his classic 1927 collection of poems emulating African American sermons, God’s Trombones, James Weldon Johnson said silence is one of the essential stylistic elements by which congregations instantly know one preacher from another.

Some prominent preacherssuch as the mid-20th century giant of the black church, Howard Thurmanwere known for pausing for minutes on end during their preaching and public prayer. In churches crowded with people eager to shout and sing, such lingering silences became more tension-filled the longer they wore on. “These periods of silence induced a sense of awkwardness initially,” the Baptist minister Jerry M. Carter writes of Thurman’s pauses. “But the climate produced by silence, when coupled with relevant content, is what makes for a powerful preaching moment.”

Creating such moments is a high-wire act. “This takes a degree of confidence,” Neuhaus said of drawn-out, intentional sermon pauses. “The uncertain preacher is eager to get through it, lest he lose the point or the people’s attention.” If most preachers were to try it, the Christianity Today editor Galli adds, “people would likely fidget, wondering if we had simply forgotten what we were going to say.”

But for experienced preachers, silence can be used in exactly the opposite way: to demonstrate full control over the moment and the craft. Obama’s eulogy is an indication of the confidence he seems to feel midway through his second term. This speech, through responding to tragedy, may be remembered as one of the most triumphant of his presidency. Singing certainly has something to do with that, but so does silence.