Ferguson, one of the most prominent, intellectually provocative, and contrarian historians at work today, argues that the world is shaped by the interactions of entrenched hierarchies and disruptive upstart “networks.” Drawing from myriad disciplines, from economics and sociology to neuroscience and organizational behavior, Ferguson contends that the importance of social networks has been traditionally overlooked and that his book is a corrective. With a broad sweep, he looks at these networks from the 15th century and the printing presses that challenged the Catholic Church and monarchy, to Silicon Valley today, where informal social networks disrupt traditional ways of doing things.