The Enlightenment's roots go back to the Renaissance, when many of the Medeaval concepts were finally displaced. The development of Art and expansion of Trade and Banking, among other social changes that occurred in the late 1400's brought about the sense that the world was comprehensible and profitable; that you could navigate to a place with fair certainty and make money through trade, and not fall off the edge. Through the use of Man's reason, everything could be understood. The reexamining of Mankind's place in the cosmos, and exactly how that cosmos worked brought about new philosophies. The authority of the Church was questioned; the Scientific Process was established, in which evidence had to be presented to conclude truths, not just a willingness to accept truth from authorities, ancient or otherwise. These questions fostered the intellect; universities were founded, new technologies, like the printing press, were applied, and the amount of information and the rates of literacy soared. Philosophers began to question the relationship of individuals to their government; the philisophical foundations of the American and French Revolutions are found in the writings of a century and a half earlier. The Age of Reason ran concurrently with the Enlightenment; breakthroughs in physics and chemistry brought about a revolution in science. New concepts about how economies worked raised the standard of living for almost all of humanity.
The revolutionary component of the Enlightenment was that Mankind's reason challenged and overturned the "institutional inertia" that had been in place for centuries, and in some areas, like science, for millennia. Church authority weakened, monarchy was questioned and overthrown, science brought new discoveries, and economics brought new wealth. We are still benefiting from its progress.