In 1833, Ralph Waldo Emerson, a New England pastor who’d recently given up the ministry, delivered his first public lecture in America. The talk was held in Boston, and its nebulous-sounding subject (“The Uses of Natural History,” a title that conceals its greatness well) helped lay the groundwork for the nineteenth-century philosophy of transcendentalism. It also changed Emerson’s life. In a world that regarded higher thought largely as a staid pursuit, Emerson was a vivid, entertaining speaker—he lived for laughter or spontaneous applause—and his talk that day marked the beginning of a long career behind the podium. Over the next year, he delivered seven talks, Robert D. Richardson, Jr., tells us in his 1996 biography, “Emerson: The Mind on Fire.” By 1838, he was up to thirty. Then his career exploded. In the early eighteen-fifties, Emerson was giving as many as eighty lectures a year, and his reputation reached beyond the tight paddock of intellectual New England. The lecture circuit may not have shaped Emerson’s style of thinking, but it made that style a compass point of nineteenth-century American thought.

Whether Emerson has a modern heir remains an open question, but, more than a century after his death, the speaking trade he enjoyed continues to thrive. In this week’s issue of the magazine, I write about TED, a constellation of conferences whose style and substance has helped color our own moment in public intellectual life. As many media companies trading in “ideas” are struggling to stay afloat, TED has created a product that’s sophisticated, popular, lucrative, socially conscious, and wildly pervasive—the Holy Grail of digital-age production. The conference serves a king-making function, turning obscure academics and little-known entrepreneurs into global stars. And, though it’s earned a lot of criticism (as I explain in the article, some thinkers find TED to be narrow and dangerously slick), its “TED Talks” series of Web videos, which so far has racked up more than eight hundred million views, puts even Emerson to shame.

Why? Trying to understand the appeal of TED Talks, I found myself paying close attention to the video series’ distinctive style and form. Below, five key TED Talks, and what they illuminate about the most successful lecture series ever given.

1. The TED Moment: Bryan Stevenson on Incarceration and Injustice

At TED’s flagship conference this past spring, in Long Beach, California, Bryan Stevenson, who heads the Equal Justice Initiative, took to the stage to give a TED talk for the first time. He prepared less exhaustively than many TED presenters do: he told me that he’d planned his remarks in large part on the flight over. (Stevenson, whose work included arguing Miller v. Alabama before the Supreme Court later that month, had a busy spring.) Yet his lecture was a perfect expression of everything a TED talk, at its best, achieves. Stevenson approaches an issue of national concern—in this case, hidden prejudices and injustices of America legal procedure—through a series of personal stories, giving the issue a warm emotional valence. As the talk drew to a close, you could feel excitement gathering in the Long Beach theatre; when Stevenson finished, he received a long, ecstatic standing ovation—the biggest of the conference. Many veteran TEDsters call this kind of thrill a “TED moment.”

2. The Next Big Thing: Jeff Han Demonstrates Multi-Touch Technology

TED has always enjoyed a strong connection with Silicon Valley. Over the years, the conference has unveiled major products (like Adobe Photoshop) and served as an early showroom for other innovations (like the Apple Macintosh). In February, 2006, a year before the first appearance of Apple’s iPhone, Jeff Han, an N.Y.U. researcher, demonstrated multi-touch technology on TED’s stage. For the crowd in Monterey, California, where the conference was then held, and for Web viewers later that year, the interface was a revelation. Hear people murmur with astonishment as Han explains pinch-zoom gestures, or as he types on a screen keyboard. Han’s talk, from the first conference filmed for Web distribution, also shows TED’s sophisticated camera work and editing. Frequent shifts in perspective, plus occasional cuts to a feed from the multi-touch screen itself, help to give Web viewers the best, most intimate seat in the house.

3. The Theatrical Polish: Susan Cain on Introversion

Many of the most popular TED talks share a strong narrative and a polished theatrical style. In preparation for her first TED talk, Susan Cain, who’d just published her first book and had little public-speaking background (the book was about introversion), worked with an acting coach, Jim Fyfe, to polish her stage style. Note her narrative reënactment and use of props—a common TED gambit—to turn a counterintuitive, data-based argument about the leadership potential of introverts into a miniature theatre piece. Cain’s début on the TED stage had an exceptional response, getting hundreds of thousands of viral views in its first day online.

4. The Breakthrough: Jill Bolte Taylor on Her Stroke

TED’s live audience, like its speakers, tends to represent the upper echelons of education, public achievement, and wealth: everyone from Al Gore to Pat Mitchell and Bill Gates has sat in TED’s seats as spectators, and the conference sells its pricey tickets through an application that includes essays and references. What do these people want that they can’t already get? Often, it seems, they are looking for a kind of transcendence, one that lies past the rational and erudite work at which they excel. In narrating a stroke that afflicted her left hemisphere, Jill Bolte Taylor establishes her ample intellectual credentials and then describes breaking beyond them. In the last part of the 2008 talk, Taylor allowed emotion to overtake her, describing the beauty of a world unmarred by analytical intelligence. Her analytically trained audience ate it up.

5. Thinking about Thinking: Sir Ken Robinson on Education

The most popular TED talk of all time contains no slides, no props, no technology, and very little movement—a success that seems anomalous until you look closely at its argument. In this 2006 TED lecture, Sir Ken Robinson fires a shot over the bow of modern public education, suggesting that schooling is, basically, set up to guide students toward becoming university professors. As a result, he argued, they’re led away from their natural creative impulses. Robinson’s lecture captures a common project of many TED presentations and, in fact, of the conference itself: closing the rift between a systematized, cumulative idea of higher thought (as we find in academia) and a more personal, directly applicable model (an ideal of entrepreneurship and the arts). His talk’s wild popularity suggests that effort strikes a cultural nerve.

Illustration by Mr. Bingo.