Historian Peter Gay once wrote that the Enlightenment represented a "recovery of nerve," a period in which people for the first time in centuries embraced real, actual change:
Fear of change, up to that time nearly universal, was giving way to fear of stagnation; the word innovation, traditionally an effective form of abuse, became a word of praise.
Today, historians take a more complex view of the Enlightenment, but many would still agree that it represented a fundamental change in the way that western thinkers viewed the world. Particularly important was the belief, common to most Enlightenment philosophes, that human institutions, including government, systems of labor, even religion itself, ought to be subjected to criticism using reason. It was this spirit of criticism that Gay characterized as a "recovery of nerve": the willingness to question formerly sacred institutions. Voltaire questioned organized religion, Beccaria crime and punishment, Diderot slavery, Rousseau the foundations of civil society and human nature, and Hume epistemology and the limits of reason itself. The questions they raised yielded no easy answers, and many aspects of the Enlightenment worldview were under siege even during the eighteenth century. But the Enlightenment marked the enshrinement of a rationalistic worldview, informed by science, that still persists today.