Published in 2000, “The Tipping Point” rapidly reached a tipping point. In the blink of an eye, it seems, Malcolm Gladwell’s argument that social epidemics are spread by a small number of special people, whom he calls mavens, connectors, and salesmen, became conventional wisdom.

According to Jonah Berger, an assistant professor of marketing at the Wharton School at the University of Pennsylvania, conventional wisdom is wrong. More important than the messenger, Berger points out, is the message. In “Contagious,” he identifies six ingredients or principles that are associated with messages, products, or ideas that go viral. Summarized in an easy-to-remember acronym (STEPPS), they are: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories.