Whether she’s weighing into Amazon or defending fantasy against the slights of literary novelists, Ursula Le Guin is always good value. This month on her blog, a request for a list of her top 50 books led to a meditation on the books that had failed to change her.

“What books didn’t influence me?” she writes. “If only someone would ask that! I’ve been waiting for years to answer it. Atlas Shrugged, by Ayn Rand, I will say, had absolutely no influence on me except to cause hours of incredulous boredom. I thought in all fairness I ought to try The Fountainhead. I gave up on page 10.”

Given the ideological baggage of Rand’s novels, and the espousal of her philosophy by the new right in the US, Le Guin’s stand is as much political as aesthetic, but it raises the question: what does it mean to be influenced by a book?

This question is easier to answer if a book sets out to make converts. Asked by the New York Times which book he would require Barack Obama to read, the Pulitzer prize–winning author Jared Diamond named Niccoló Machiavelli’s 500-year-old treatise on leadership, The Prince.

He explained that while Machiavelli “is frequently dismissed today as an amoral cynic who supposedly considered the end to justify the means,” he is, in fact, “a crystal-clear realist who understands the limits and uses of power.” Whether Obama has heeded Diamond’s advice is unknown.

But what of softer forms of influence? It’s unlikely that Vladimir Nabokov’s Lolita has created many paedophiles, but – as novelist David Lodge pointed out – it played a key role in the war against censorship, and has been a touchstone for literary stylists ever since.

Nabokov himself was contemptuous of the idea of influence, insisting in a Paris Review interview that James Joyce “has not influenced me in any manner whatsoever”; moreover that he was careful not to learn anything from Gogol.

He continued: “Brecht, Faulkner, Camus, many others, mean absolutely nothing to me, and I must fight a suspicion of conspiracy against my brain when I see blandly accepted as ‘great literature’ by critics and fellow authors Lady Chatterley’s copulations or the pretentious nonsense of Mr Pound, that total fake.”

Part of Nabokov’s point is that where literary influence is concerned, quality of thought and style are indivisible. He lambasted “Punningans Wake in which a cancerous growth of fancy word-tissue hardly redeems the dreadful joviality of the folklore and the easy, too easy, allegory”.

How a reader perceives this quality, however, can change. As a young teenager I felt passionately transformed by Tess of the D’Urbervilles’ insights into the injustices of class and gender. Now that I’m older it feels like “a conspiracy against my brain”; a piece of manipulative melodrama.

At the same age I was bored to tears by Dickens’ Bleak House, dismissed Esther Summerson as a wet weekend, and would have laughed if anyone had told me how powerful its interminable portrayal of cultural and legal deadlock would become for me decades later. The novel’s length, and Esther’s passivity, are intrinsic to its impact.

What are the books that didn’t influence you?