The Enlightenment represents the first time since Democritus that philosophers began to systematically question religious explanations for material phenomenon, instead looking for strictly materialistic explanations that were consistent with our understanding of the temporal plane. In particular, this is when science began to challenge the power of the Western religious authorities, which also challenged the principle of rule by divine right. In addition to the appearance of religious skepticism and scientific explanations, this is the period when revolutions against inherited rule challenged the kings and queens of Europe. This period is also associated with a dramatic increase in literacy in Western countries, which makes an interesting contrast with, for example, China, where the complexity of the written language served as an obstacle to higher rates of literacy for several centuries. In general, high rates of literacy are inversely correlated with institutional power and correlated with personal liberty in citizens. The worldwide spread of democracy over the last 200 years is a direct result of intellectual changes associated with the Enlightenment, but the chapter also reviews why the transition to democracy has not been universal.