Although the ideals popular during the Enlightenment will not radically shake the European (and, in fact, the worldwide) political scene for another hundred years or so, we ought not to continue anachronistically; so we will quickly put a few of those ideals on the table now, and we will have to keep them in the back of our memory for later. The great thinkers of the Enlightenment are no unfamiliar names: John Locke, Thomas Hobbes, Denis Diderot, Jean-Jacques Rousseau, René Descartes, Adam Smith, and Voltaire, just to name a few. Each of these (and several others) is important to the development of Western philosophy, but there is simply too much there to examine each of their writings and ideas. So, not to neglect the others but only for the sake of time, we will focus mainly on Rousseau, whose philosophies will directly influence the future of the art we will be looking at.
But first it is essential to understand that around this time the idea of what the French called bon sauvage (the philosophical concept of the noble savage) was being established. Perhaps directly influenced by the Colonials, who were observing and interacting with the native "Indians" first-hand, European philosophers had to rethink the nature of mankind upon discovering what they saw as a totally different race of humanity. Despite the wholesale slaughter of countless natives via their own expatriates, the European populace slowly fell toward favoring the "savage" because of the belief in man's inherent state of purity when left uncorrupted by society and technology.
This concept was further established (but certainly not first thought of) by Jean-Jacques Rousseau, a writer, philosopher, and musician who lived during the latter half of the Enlightenment Period. Rousseau's novel Émile propagated the notions that children are born pure, and that it is the culture of society which corrupts the mind and heart of innocence in youth. Children, he argued, should be raised in the country, in nature, like peasants (or savages) in order to mature more naturally (and, consequently, more ideally). It was here that the word "kindergarten" originated—a German word comprised of the words for "child" and "garden." Rousseau's idea of education was one which sought to put children in better touch with Nature and the pure, unadulterated pastoral world of God's creation. Through natural unfolding, left alone to grow in countryside settings away from technological influence, children, Rousseau asserted, would develop as purer human beings than even the greatest of his contemporaries. This ideology is still seen all around us today in our own education system. Early American leaders and entrepreneurs bought into this philosophy and applied it to their construction of college campuses and universities across the nation. This is why so many colleges are decorated and supplied with verdant foliage, to the resemblance of a public park or garden grove. It's not just for looks; it stems (no pun intended) from the idea that our youth should be raised and educated in nature. Most universities in the United States today are still kept to look this way.
With this notion the only logical conclusion to arrive at is that truth, purity, and the holiness of God can be found in Nature, since it is through living in harmony with the natural world (like a savage) that one becomes truly noble. We have seen a focus on pastoral landscapes in art before, during the Dutch Baroque period of art; but note the distinction. The Dutch Baroque artists were acting from religious motivations—Protestant motivations—in effort to express the idea that the natural man could be holy without the intermediation of the Catholic Church; and the humble peasant could, in his own plowing-field, be considered as holy as—or more holy than—the most decorated bishop in the Vatican. It was about religion and the Protestant view of man's direct relationship to God. The Enlightenment view of Rousseau is very different. It erases God and claims that mankind can be perfect in and of himself if only raised to live in harmony and peaceful coexistence with the natural world that God created. Since God's creation is inherently good, a savage living off the land is closer to holiness than a nobleman. No longer is it about relating to God through Nature and everyday observances and living; it's about becoming ideally perfect in and of one's own human nature through separation from civilization. This is a very important concept, and I may not be explaining it clearly enough; perhaps a little later on we can discuss it some more. A simple way to tell the difference between the two mindsets is in the physical manifestation of their art. The Dutch Baroque artists, you will recall, often included a spire, or church steeple, in their landscape paintings as a symbol of their humble religious devotion, a reminder to serve God faithfully; the later Romantics, as we will see, paint equally lovely images of natural landscapes—but without the spire. This apotheosis of Nature will become grandiosely significant later on, but for now it is merely introduced.