"The more that is at stake, the greater the financial cost, and the higher the reputational risk, the more proof or evidence that is needed… The more proof that is needed, the more important multiple sources become. We need to find similar but diverse others who provide consistent perspectives, and concentrate those sources in time so their benefit doesn’t evaporate."

Jonah Berger's a world renowned expert on behavior change, social influence, word of mouth, and why products, ideas, and behaviors catch on.