Well, it looks like it is finally calming down. Patios are being cleaned off. Ice buckets are being put away. But only after the ALS Ice Bucket Challenge generated more than $100 million in donations in a single month, a staggering amount considering the organization took in only $2.5 million for all of 2013. How in the world did this happen?

Why is it that some ideas take flight and spread like wildfire, while others, seemingly equally worthy, fall mostly on deaf ears? Why did the Ice Bucket Challenge go viral, raising millions without spending a penny on marketing, while other non-profits can never seem to lift their message above the noise?

Just as some species share traits that make them more likely to spread through evolution-enjoyable orgasms being one example-so do some ideas have traits that put them at a distinct advantage to captivate and spread. Big ideas get noticed; Selfless ideas inspire action; Simple ideas write us into the story. Understand how to make your ideas big, selfless and simple and you will be able to control growth.

Long before we were pouring millions of gallons of ice water on our heads, there was an even more compelling case study in contagion: British punk rocker Bob Geldof. In the fall of 1984, Geldof was about as flatlined and rut-stuck as you can get in the rarified air of rock 'n' roll. His band, the Boomtown Rats, had had some regional success in the United Kingdom, but none of its songs had climbed higher than number 67 on the U.S. charts. And then, their seemingly promising single, "I Don't Like Mondays," hit the airwaves. After word leaked out that Geldof had written the song about a woman shooting schoolchildren from her apartment window, the song was boycotted by the radio industry.

Geldof was broke, fast fading from public memory, and completely alone. Then one dreary London evening in mid-November 1984, as he sat slouched in front of his television, BBC aired a documentary about a hundred-year drought that was threatening millions of Ethiopians with starvation.

The next day Geldof began calling fellow musicians, suggesting a group single to benefit starvation victims. With the passion of the idea behind him, he was able to pull together the core of British rock royalty in only three weeks to record "Do They Know It's Christmas?" The record generated hundreds of thousands of dollars for famine relief.

But the momentum didn't stop there. Bakers began donating food. Schools held canned-goods drives. Children were knitting blankets. Like a spiraling contagion, people enlisted in the cause. As the momentum spread to America, Geldof latched on to an even bigger idea. Conceived in January 1985, the Live Aid concert was successfully birthed less than seven months later.

The fact is that absolutely nothing in the history of entertainment-not Woodstock or any other mass event-comes anywhere close to matching Live Aid in scope, in numbers, in impact, or in the grandeur of its concept. An estimated 1.5 billion viewers in 100 countries watched at least some part of the 16 hours' worth of performances. When the final tally was in, Live Aid had raised a little over $245 million from every corner of the world.

How did something so epic happen so quickly? What was it about Live Aid that so caught the world's attention that one-third of all the people alive on the planet would tune in to watch it and collectively donate just shy of a quarter billion dollars to famine relief? What do famine relief and self-inflicted refrigeration have in common?