Modernity may be said to start with the invention of the printing press, as ordinary people began to read religious texts for themselves, without priestly mediation and interpretation. So historians generally start “the early modern period” with the Reformation and the proliferation of “radical sects,” many of them utopian, such as the Diggers in England. (There had been outbreaks of communal democracy before this, e.g., the Lollards or some earlier apostolic Christians/Jews).
So from roughly the 16th century onward through European wars and revolutions, often couched in the language of religious controversy, modernity led to the contentious emancipation of women, Jews, and ordinary people, not without strenuous objection from the ruling aristocracies of Europe, who were themselves sharply divided but who united against “the People” upon whom they projected their own paranoia. (See the famous and entertaining fight between royalist Robert Filmer and Whiggish John Locke here: https://clarespark.com/2009/08/24/the-people-is-an-ass-or-a-herd/.)
Modernity generated supporters and antagonists in the world of culture. It would be nice and easy to contrast order-loving neoclassicists with Romantics, but the Romantics were themselves divided, as were some neoclassicists. For instance, Wordsworth and Coleridge started out as enthusiasts for the French Revolution, but balked at the Jacobin takeover, worship of “the Goddess of Reason,” and the Reign of Terror, turning then sharply against science and Enlightenment. These were “right-wing” Romantics, to be sharply contrasted with the Promethean Lord Byron, the most prominent of the “left-wing” Romantic poets. ( The Danish critic Georg Brandes is very good on these distinctions.)
Just as people sorted themselves out according to how they felt about the French Revolution and its aftermath, the same happened after the Soviet coup of 1917. But the cat was out of the bag: the interior life was now fodder for artists and writers, and those “realists” and “naturalists” so beloved by the Soviet nomenklatura, were competing with those wild men and women influenced by Freud, Jung, and other explorers of the psyche. Some usually conservative writers, like Herman Melville, vacillated between Romanticism and neo-classicism, leading to the sharp divisions among Melville critics who find these turnabouts anxiety-provoking.
So modernity generated a usually reactive modernism. Modernism is an entirely different kettle of fish from “modernity,” being mostly a movement in the arts in reaction to the idea of progress, a shibboleth that had taken a big hit with the Great War. Even before the war, the rise of women (including “the moral mother” displacing paternal authority in the home), cities, industrialism, the loss of the agrarian myth, “the death of God,” mass politics, comparative luxury, and cultural pluralism inspired fears of decadence and mob rule. Even before WW1, Freud, Marx, and Darwin all discombobulated elites and in various ways inspired fears of decadence and the femme fatale—an all-purpose scary symbol representing all these trends (see https://clarespark.com/2009/10/23/murdered-by-the-mob-moral-mothers-and-symbolist-poets/).
The Great War that ended the lengthy “balance of power” among European states seemed like the logical culmination to these vast transformations, and the war itself that enabled the Soviet coup led to an earthquake in culture that made the French Revolution look tame, but also causal in imposing “state terror.”
I have written extensively about the turn toward the interior psyche in all its moods, particularly primitivism as ritual rebellion, and also about the recurrent image of Pierrot, an example of the alienated artist as murderer, as Cain, as zany. In prior blogs, I have mentioned Hemingway, James Joyce, Virginia Woolf, and Sartre, all experimenters with language and form and all modernists in revolt against some aspect of “modernity.” [I have not dealt with “postmodernity here, but it is directed against science and enlightenment too, viewed perhaps as too bourgeois.]
To end with a “relevant” observation, I would guess that the rise of the moral mother (along with the emancipation of Jews) was the most important and relatively neglected of the cataclysmic developments all too briefly outlined above. Not enough has been made of the linkage between antisemitism and misogyny. (None of my speculations is in the Wikipedia discussion of http://en.wikipedia.org/wiki/Modernity.)
Many conservatives look longingly back at the time when “rational” men, not “irrational” women, ruled the roost. It is why I reject the “right-wing” strategy for taking back the culture from “the left.” (https://clarespark.com/2014/07/01/the-rightist-culture-war-strategy-wont-work/.)