Reason is to the philosopher what grace is to the Christian. Other men walk in darkness; the philosopher, who has the same passions, acts only after reflection; he walks through the night, but it is preceded by a torch. The philosopher forms his principles on an infinity of particular observations. He does not confuse truth with plausibility; he takes for truth what is true, for forgery what is false, for doubtful what is doubtful, and probable what is probable. The philosophical spirit is thus a spirit of observation and accuracy. ~ Dumarsais, French philosopher and grammarian, and a major contributor in the philosophy emerging from the Age of Enlightenment.
The Age of Enlightenment was an era when reason, argument, and critical thinking came to be considered more valuable than unfounded superstitious beliefs, blind faith, and irrational thinking. Religious and traditional theories about life and society existed in Western philosophy for a long time. Clergymen dominated the thinking of people, and science was branded to be witchcraft, blasphemy, and heresy.
The Enlightenment marked the end of hypocrisy and irrational thinking about tangible concepts, such as the universe, life, and living in general. With the generation of some genius thinkers fighting to defend theories of science and promoting reasoning, this period kick-started a major transition phase for Western society.
It is the 18th century that is regarded as the era of Enlightenment, but its roots go back to the 13th and 15th centuries. It all started from the recuperation of Aristotelian logic by Thomas Aquinas in the 13th century. We all know about the famous Greek philosopher, Aristotle, who challenged faith and beliefs of clergymen by means of logic. In the centuries to come, the world witnessed a new breed of scientific, rational thinkers. It was during this period that the world was stormed by scientific revolution, with the likes of Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei, and Sir Issac Newton formulating some of the most fundamental theories in modern science. However, the Catholic Church never accepted these advancements, since they went against its teachings, and threatened to reduce its power and hold over the masses.
Some of the most prominent philosophers of the Age of Reason were Rene Descartes (1596 - 1650), Benedict Spinoza (1632 - 1677), Francis Bacon (1561 - 1626), Thomas Hobbes (1588 - 1679), John Locke (1632 - 1704), David Hume (1711 - 1776), Jean-Jacques Rousseau (1712 - 1778), Immanuel Kant (1724 - 1804), Thomas Paine (1737 - 1809), François-Marie Arouet aka Voltaire (1694 - 1778), and Thomas Jefferson (1743 - 1826). The philosphy of Enlightenment spread in European colonies, and began to transform people's views about modern science and religion.
During this time, Encyclopédie, one of the greatest publications ever known in human history, was published. In Encyclopédie, a large number of philosophers contributed their articles. Encyclopédie became the basis of the French Revolution in 1789, and it also gave rise to theories of Capitalism. Much of our present-day thinking is based on logic, modern science, and rational thought.
In culmination, it can be said that the age of Enlightenment brought an end to the domination of churches and religious dogmas, though the split between science and religion is still being fought today.