A contrapuntal essay
In "The Relevance of Animal Experimentation to Roman Catholic Ethical Methodology," James Gaffney discusses the medieval church view (most prominantly expressed by Thomas Aquinas) that cruelty to animals was not inherently sinful, but that cruely to animals could lead one to a cruel disposition and cruelty toward humans. Gaffney writes
"Shakespeare reminds us that such ideas were current later in the Renaissance. thus, in Cymbeline, the queen's plan to test slow and painful poisons on 'such creatures as we count not worth the hanging--but none human' elicits from her physician the admonition that 'your highness shall from this practice but make hard your heart.'"
One doesn't have to look hard to find the ideas current at a time working their way into works of literature (and I'm reminded of John Fowles' suggestion that bad novels tell us more about the time period they were written in than good novels). Sometimes this is in mere passing, though sometimes writers particularly focus on exploring the ideas of the time. Mikhail Bakhtin writes that
"As an artist, Dostoevsky did not create his ideas in the same way philosophers or scholars create theirs--he created images of ideas found, heard, sometimes divined by him in reality itself, that is, ideas already living or entering life as idea-forces. Dostoevsky possessed an extraordinary gift for hearing the dialogue of his epoch [...] He heard both the loud, recognized, reigning voices of the epoch, that is, the reigning dominant ideas (official and unofficial), as well as voices still weak, ideas not yet fully emerged, latent ideas heard as yet by no one but himself, ideas that were just beginning to ripen, embryos of future worldviews."
And indeed, in Dostoevsky's great novels, he seems to tweak out the consequences of the religious and political thoughts and movements of his era.
I actually think it is primarily new scientific theories, new discoveries, and technological advancements that lead to a zeitgeist, a worldview common to a culture of a place and time. It is also political and economic events, but it is often new scientific insight that advances people to new ideas, new ways of seeing the world. Think of the giant shifts in thought after Columbus's trip to America. Think of the astronomical discoveries about the earth's place in the universe. Of human forays into outer space. Of life at the cellular level. Of how the printing press, railroads, flight, telephone, television, internet change us.
I also think of Darwin, and more broadly the new geological and biological ideas of the 19th century. Isn't reaction to such new ideas central to Victorian thought (or do I only think this because I've read The French Lieutenant's Woman too many times)? Which naturally brings me to Alfred Lord Tennyson. In In Memoriam A.H.H., Tennyson expresses his anxiety over the new scientific theories on geology and biology. He does not "invent" these ideas. I also doubt he was the first or only Victorian to react to Lyell in the way that he did. But you can read Tennyson's poetry if you want to explore the Victorian zeitgeist, if you want to see how Victorians responded to the scientific insight at the time. It's not the only reaction, but it is a prominent reaction. In Memoriam A.H.H. is perhaps an expression through poetry of the spirit of the time.
As I said, it is scientific insight, whether it be theory, discovery, or advancement, that moves the zeitgeist. But sometimes in literature these ideas are exposed or explored. Literature may articulate the consequences of an idea.