Social norms of the time included the idea that humans are rational creatures; that we can know this world through the power of reason. Although the idea of "reason" meant different things to various thinkers (Wilkie and Hunt 7), most people of the Enlightenment saw reason as a power for good in their world. Whereas earlier thinkers in the Renaissance thought that the world could be best understood through Scripture, the divine intervention of God, and through the study of classical authors (especially the writers of Greece and Rome), thinkers of the Enlightenment thought that the world was best studied through the powers of human reason and observation. The ultimate example of this last idea is the development of the idea of the scientific method.
In 1687, Issac Newton published his Principia Mathematica, which described the physical world in mathematical terms. The thinkers of the Enlightenment saw the physical world as a mechanical object which could be understood through science and reason, not through God or divine scriptures. Today, most of the physical and social sciences continue to use use the scientific method as their primary method of inquiry (that is, of knowing the world). Many thinkers of the Enlightenment felt that the orderly world described in Newton's work impelled them to seek order in their social and political worlds, too -- by the use of reason rather than by the use of scriptures or religious ideas. For example, in Gulliver's Travels we see the narrator extol the virtues of the "rational" social order of the Houyhnhnms and deplore the "irrational" social arrangements and character of the Yahoos.
In politics, nations emerged from the small kingdoms of Europe and coalesced around the idea of a national character under one political umbrella. The political stability granted by nation-states was seen as a way to meet the need for order in society and politics; the nation was thought of as a "natural" outgrowth of human social needs (not as a divinely-inspired organization shaped by God, as in earlier times).
Emotion was distrusted and regarded as the opposite of reason. Many in the Enlightenment regarded emotion and passion as the opponent of reason. For example, in Tartuffe, we see that reason is valued and passion seen as a threat to all that is good in society: ruled behavior, stability, order, predictability, human relationships and harmony.
Deism sees God as a supreme spiritual being who is revealed through humanity's powers of reason (not as a being who is revealed in "miracles" or Scripture). To the Deists, God was a divine clockmaker who set the physical world in motion, ordained the physical laws of physics for its workings, and then stepped back to view the workings of this machine. Deism suggests that God does not change the natural laws of the physical world to suit the whims of humanity or individuals. Although the Deists held a belief in God the Creator, they rejected clerical authority, revelation, original sin, and miracles.
Literature was seen as having as its purpose to delight (to entertain) and to instruct (to show readers how to live their lives through rational action and to show readers the results of not acting rationally); literary models were taken from the Greek and Roman past. These models from Greek and Roman literature were seen by many writers of the Enlightenment as embodying strict rules of plot, structure, character, and style, which should be emulated.
Alexander Pope, in his "Essay on Man," lays out the best explanation for this metaphor. The universe is an orderly creation, set in motion by a Creator God. Every aspect of creation has a prescribed place and as long as all created entities remain in that prescribed place, all will go well. Humans have Reason to set them above the animals, but our place in the Great Chain of Being is below the angels; we have no business questioning the ways of God. Our job is to understand our own nature and to regulate it.
"Know then thyself, presume not God to scan;
The proper study of Mankind is Man" (Epistle II, 1-2).
The business of humanity is to recognize that we are "naturally" a mixture of vices and virtues and to use Reason and moderation to regulate these two sides of ourselves. Pope sees Passions as the irrational side of human nature, but does not see them as being evil. He thinks such passions are necessary for human accomplishments, but that they must always be regulated by Reason. He suggests that evil is an illusion, that what human beings call evil may in fact be good in a larger, humanly unknowable plan for the universe. He asserts that "One truth is clear, WHATEVER IS, IS RIGHT."