<P> Bertrand Russell saw the Enlightenment as a phase in a progressive development which began in antiquity and that reason and challenges to the established order were constant ideals throughout that time . Russell said that the Enlightenment was ultimately born out of the Protestant reaction against the Catholic counter-reformation and that philosophical views such as affinity for democracy against monarchy originated among 16th - century Protestants to justify their desire to break away from the Catholic Church . Though many of these philosophical ideals were picked up by Catholics, Russell argues that by the 18th century the Enlightenment was the principal manifestation of the schism that began with Martin Luther . </P> <P> Jonathan Israel rejects the attempts of postmodern and Marxian historians to understand the revolutionary ideas of the period purely as by - products of social and economic transformations . He instead focuses on the history of ideas in the period from 1650 to the end of the 18th century and claims that it was the ideas themselves that caused the change that eventually led to the revolutions of the latter half of the 18th century and the early 19th century . Israel argues that until the 1650s Western civilization "was based on a largely shared core of faith, tradition and authority". </P> <P> There is little consensus on the precise beginning of the Age of Enlightenment, though the beginning of the 18th century (1701) or the middle of the 17th century (1650) are often used as epochs . French historians usually place the period, called the Siècle des Lumières ("Century of Enlightenments"), between 1715 and 1789, from the beginning of the reign of Louis XV until the French Revolution . If taken back to the mid-17th century, the Enlightenment would trace its origins to Descartes' Discourse on the Method, published in 1637 . In France, many cited the publication of Isaac Newton's Principia Mathematica in 1687 . It is argued by several historians and philosophers that the beginning of the Enlightenment is when Descartes shifted the epistemological basis from external authority to internal certainty by his cogito ergo sum published in 1637 . As to its end, most scholars use the last years of the century, often choosing the French Revolution of 1789 or the beginning of the Napoleonic Wars (1804--1815) as a convenient point in time with which to date the end of the Enlightenment . </P> <P> In the 1944 book Dialectic of Enlightenment, Frankfurt School philosophers Max Horkheimer and Theodor W. Adorno argued: </P>

Who provided the rationalization of existence based upon reason and not supernatural factors