Horchow's daughter, Sally, told me a story of how she once took her father to a new Japanese restaurant where a friend of hers was a chef. Horchow liked the food, and so when he went home he turned on his computer, pulled up the names of acquaintances who lived nearby, and faxed them notes telling them of a wonderful new restaurant he had discovered and that they should try it. This is, in a nutshell, what word of mouth is. It's not me telling you about a new restaurant with great food, and you telling a friend and that friend telling a friend. Word of mouth begins when somewhere along that chain, someone tells a person like Roger Horchow.

Here, then, is the explanation for why Paul Revere's midnight ride started a word-of-mouth epidemic and William Dawes's ride did not. Paul Revere was the Roger Horchow or the Lois Weisberg of his day. He was a Connector. He was, for example, gregarious and intensely social. When he died, his funeral was attended, in the words of one contemporary newspaper account, by "troops of people." He was a fisherman and a hunter, a cardplayer and a theater-lover, a frequenter of pubs and a successful businessman. He was active in the local Masonic Lodge and was a member of several select social clubs. He was also a doer, a man blessed — as David Hackett Fischer recounts in his brilliant book Paul Revere's Ride — with an "uncanny genius for being at the center of events." Fischer writes:

When Boston imported its first streetlights in 1774, Paul Revere was asked to serve on the committee that made the arrangement. When the Boston market required regulation, Paul Revere was appointed its clerk. After the Revolution, in a time of epidemics, he was chosen health officer of Boston, and coroner of Suffolk County. When a major fire ravaged the old wooden town, he helped to found the Massachusetts Mutual Fire Insurance Company, and his name was first to appear on its charter of incorporation. As poverty became a growing problem in the new republic, he called the meeting that organized the Massachusetts Charitable Mechanic Association, and was elected its first president. When the community of Boston was shattered by the most sensational murder trial of his generation, Paul Revere was chosen foreman of the jury.

Had Revere been given a list of 250 surnames drawn at random from the Boston census of 1775, there is no question he would have scored well over 100.

After the Boston Tea Party, in 1773, when the anger of the American colonists against their British rulers began to spill over, dozens of committees and congresses of angry colonists sprang up around New England. They had no formal organization or established means of community. But Paul Revere quickly emerged as a link between all those far-flung revolutionary dots. He would routinely ride down to Philadelphia or New York or up to New Hampshire, carrying messages from one group to another. Within Boston as well, he played a special role. There were, in the revolutionary years, seven groups of "Whigs" (revolutionaries) in Boston, comprising some 255 men. Most of the men — over 80 percent — belonged to just one group. No one was a member of all seven. Only two men were members of as many as five of the groups: Paul Revere was one of those two.

It is not surprising, then, that when the British army began its secret campaign in 1774 to root out and destroy the stores of arms and ammunition held by the fledgling revolutionary movement. Revere became a kind of unofficial clearing house for the anti-British forces. He knew everybody. He was the logical one to go to if you were a stable boy on the afternoon of April 18th, 1775, and overheard two British officers talking about how there would be hell to pay on the following afternoon. Nor is it surprising that when Revere set out for Lexington that night, he would have known just how to spread the news as far and wide as possible. When he saw people on the roads, he was so naturally and irrepressibly social he would have stopped and told them. When he came upon a town, he would have known exactly whose door to knock on, who the local militia leader was, who the key players in town were. He had met most of them before. And they knew and respected him as well.

But William Dawes? Fischer finds it inconceivable that Dawes could have ridden all seventeen miles to Lexington and not spoken to anyone along the way. But he clearly had none of the social gifts of Revere, because there is almost no record of anyone who remembers him that night. "Along Paul Revere's northern route, the town leaders and company captains instantly triggered the alarm," Fischer writes. "On the southerly circuit of William Dawes, that did not happen until later. In at least one town it did not happen at all. Dawes did not awaken the town fathers or militia commanders in the towns of Roxbury, Brookline, Watertown, or Waltham." Why? Because Roxbury, Brookline, Watertown, and Waltham were not Boston. And Dawes was in all likelihood a man with a normal social circle, which means that — like most of us — once he left his hometown he probably wouldn't have known whose door to knock on. Only one small community along Dawes's ride appeared to get the message, a few farmers in a neighborhood called Waltham Farms. But alerting just those few houses wasn't enough to tip the alarm. Word-of-mouth epidemics are the work of Connectors. William Dawes was just an ordinary man.

It would be a mistake, however, to think that Connectors are the only people who matter in a social epidemic. Roger Horchow sent out a dozen faxes promoting his daughter's friend's new restaurant. But he didn't discover that restaurant. Someone else did and told him about it. At some point in the rise of Hush Puppies, the shoes were discovered by Connectors, who broadcast the return of Hush Puppies far and wide. But who told the Connectors about Hush Puppies? It's possible that Connectors learn about new information by an entirely random process, that because they know so many people they get access to new things wherever they pop up. If you look closely at social epidemics, however, it becomes clear that just as there are people we rely upon to connect us to other people, there are also people we rely upon to connect us with new information. There are people specialists, and there are information specialists.

Sometimes, of course, these two specialties are one and the same. Part of the particular power of Paul Revere, for example, was that he wasn't just a networker; he wasn't just the man with the biggest Rolodex in colonial Boston. He was also actively engaged in gathering information about the British. In the fall of 1774, he set up a secret group that met regularly at the Green Dragon Tavern with the express purpose of monitoring British troop movements. In December of that year, the group learned that the British intended to seize a cache of ammunition being stored by a colonial militia near the entrance to Portsmouth Harbor, fifty miles north of Boston. On the icy morning of December 13th, Revere rode north through deep snow to warn the local militia that the British were on their way. He helped find out the intelligence, and he passed it on. Paul Revere was a Connector. But he was also — and this is the second of the three kinds of people who control word-of-mouth epidemics — a Maven.

The word Maven comes from the Yiddish and it means one who accumulates knowledge. In recent years, economists have spent a great deal of time studying Mavens, for the obvious reason that if marketplaces depend on information, the people with the most information must be the most important. For example, sometimes when a supermarket wants to increase sales of a given product, they'll put a promotion sticker in front of it, saying something like "Everyday Low Price!" The price will stay the same. The product will just be featured more prominently. When they do that, supermarkets find that invariably the sales of the product will go through the roof, the same way they would if the product had actually been put on sale.