The 18th century as the century in which Christianity disappeared, and was replaced by a new ideal, with a new morality based on the doctrine of natural law and an 18th-century interpretation of the stoicism of Ancient Roman Republicanism. That is the summary with which art historian Kenneth Clark ends his discussion of the French salons, right before taking about Thomas Jefferson in episode 10. In episode 11 of his 1969 series Civilisation, Clark develops this idea, of the death of Christianity, further:

For almost a thousand years the chief creative force in western civilisation was Christianity. Then, in about the year 1725, it suddenly declined and [in] intellectual society practically disappeared.

Why did it disappear? Even taking both episodes together, it doesn’t become clear. Clark merely says, as a matter of fact, that it was the case and that England was the forerunner. He does quote one authority: Montesquieu, who wrote, in about 1730, that

There is no religion in England. If anyone mentions religion people begin to laugh.

This curious disappearance of the motivating, moralising force Christianity represents, especially in Clark’s own narrative up to this point, leaves a vacuum. This, Clark admits himself. So, with people needing a belief in something outside of themselves,

they concocted a new belief which, however irrational it may seem to us, has actually added a good deal to our civilisation: a belief in the divinity of nature. (…) But the evidence of divine power which took the place of Christianity were manifestations of what we still mean by nature, those parts of the visible world which were not created by man and can be perceived through the senses.

Clark proposes, that the “faith in divine power” would ‘trickle’ back into the Western European mind through the incorporation of the “ruins of the Age of Faith” in a certain concept of Nature. And that this helped inspire the artists which he will discuss in the episode. Artists who used new forms, but above all else, worked on new subjects for their art, and looked at things in new ways.

Before the 18th century, only a handful of artists were interested in mountains. But then, in 1760, the English love of nature “touched the mind of a man of genius. Jean-Jacques Rousseau.” Until then, the “emotional response to nature” had been the prerogative of “minor poets and provincial painters.” Rousseau, however, while taking refuge on an island in Lake Bienne, became “one with nature,” realising

that our existence is nothing but a succession of moments perceived through the senses.

Clark, rather cleverly, sums up Rousseau’s philosophy in the sentence “I feel therefore I am,” calling it a “curious discovery to have been made in the middle of the Age of Reason.” He connects it to David Hume‘s work, before noting how Rousseau’s beliefs were extended from nature to man. Rousseau believed that natural man was virtuous, a belief that soon came to be widely accepted. Clark mentions and quotes three detractors of the idea, but it is fair to say that the belief that nature is somehow virtuous, while man is not, is still popular.

The remainder of the episode passes from Goethe and his influence on Darwin, to the Romantic poetry of Coleridge and Wordsworth. From them, Clark moves to painting; first to Turner, then to the Impressionists: Monet, Cézanne. This by way of an art critic, Ruskin – whom Clark has quoted as an inspiration in episode 1.

One last remark. Clark never completely explains where this ‘Cult of Nature’ comes from, nor how it could replace Christianity. Throughout this episode, he is positive about the art created by those inspired by this idea of Nature, but critical of the idea itself. Not only does he quote its critics, as mentioned before. He calls the art beautiful, and some of Ruskin’s conclusions on par with revelations from Holy Scripture. But he does not share Rousseau’s admiration for Arcadian societies, nor does he see natural man as the most moral. When commenting on the ideas of Hume, he even goes so far as to state they were

an intellectual time bomb, which after sizzling away for almost two hundred years has only just gone off, whether to the advantage of civilisation seems rather doubtful.