The Romantic Revolution by Tim Blanning.

Post-Modernism is often assumed to be a 21st Century response to the misplaced certainties of the modern era. This book raises the intriguing suggestion that an earlier movement prefigures this development by some way.

Tim Blanning makes a convincing case that the Romantic movement was a reaction against the reductionistic certainties of the Enlightenment and the dehumanising consequences of the new industries of the late 18th and early 19th Centuries.

"Three great revolutions rocked the world around the beginning of the 19th Century. The first two - the French Revolution and the Industrial Revolution - have inspired the greatest volume of literature. But the third - the Romantic Revolution - was perhaps the most fundamental, radical and far-reaching. From Wordsworth, Coleridge, Burns and Byron, to Beethoven, Rossini, Berlioz, Liszt and Wagner, to Goya, Blake, Turner and Delacroix collectively brought about an alternative revolution".
"'Absolute inwardness' is how Tim Blanning defines the essence of romanticism. From this derives virtually all the cultural axioms of the modern world: the stress on genius, originality and individual expression; the dominance of music; the obsession with sexuality, dreams and the subconscious; the role of the public as patron; the worship of art and artists."

Artists became the high priests of a new religion which venerated paintings, poetry and music. Indeed the concept of spirituality around this time shifted from the religious to the artistic. The Romantics worshipped nature - but not nature as it truly is but an idealised version of it. As a consequence they abhorred any organised religion in favour of subjective deism. The real wonder of the last two centuries has been the resilience of the church to withstand such cultural unpopularity.
The scientific revolution which had diminished the universe and life into a few objective fundamental laws was too reductionistic for the romantics who sought to affirm the value of humanity and yet they were inevitably compelled, as Blanning puts it, to resort to 'absolute inwardness' - turning inside themselves to find value and beauty. To contrast themselves from the Enlightenment which used the metaphor of daylight the romantics applied the alternative metaphor of night-time; a realm of dreams, emotion and subjectivity. For them nature was not to be tamed by the rational.
The problem for the romantic was to find themselves idealising not just nature but the world as it is; as Alexander Pope wrote:

"All nature is but Art, unknown to thee;
All Chance, Direction, which thou canst not see;
All Discord, Harmony not understood.
All partial Evil, universal Good:
and, in spite of Pride, in erring Reason's spite,
One truth is clear, Whatever is, is right."

From a Christian such an outlook is optimistic in the extreme and at variance with the world as it truly is. The world is far from ideal. So far as I know Tim Blanning is not a Christian but as with all sensitive, informed commentators their observations will chime with the Christian world-view. The book is a brilliant commentary on the culture of the West and its anomie or moral rootlessness. The Christian can affirm the empirical method of science but reject its naturalism and reductionism; that science describes the truth and nothing but the truth yet is not the whole truth. Equally the Christian can affirm the value of humanity and nature without the error of deifying them. Ultimate value is not found by 'absolute inwardness' as if we are the centre of the Universe but it is found in God, who is beyond the outermost reaches of nature. Such a God is also far greater than our inner selves. The Christian rejects the twin errors of deism and subjectivism, and avoids the false optimism of those who believe in the perfectability of humanity.

In recent years there has been an attempt to forge a Scientific History which rejects all that is past and affirms universalist values. Tim Blanning quotes Hugh Trevor-Roper's scathing analysis;
"We exist in and for our own time: why should we judge our predecessors as if they were less self-sufficient: as if they existed for us and should be judged by us? Every age has its own social context, its own intellectual climate, and takes it for granted, it is not explicitly expressed in the documents of the time: it has to be deduced and reconstructed. It also deserves respect... To discern the intellectual climate of the past is one of the most neccesary. To neglect it - to use terms like 'rational', 'superstitious', 'progressive', 'reactionary', as if only that was rational which obeyed our rules of reason, only that progressive which pointed to us - is worse than wrong: it is vulgar."

The intriguing conclusion is that what we call post-modernism may merely prove to be the logical extension of the romantic movement. The post-modernist rejects the grand narrative, teleology and rationalism. They have a strong emphasis on hedonism and the need to escape the mundane realities. Music - as the least rational of the arts - is one of the defining features of youth culture. Not to mention the use of narcotics or the fascination with the gothic. These were all features of the Romantic Revolution.
'How do you annoy a post-modernist?' 'Tell him is not original'!