Ah-ha
While walking through the village this afternoon, I idly asked myself: if pressed, could I identify specific literary works that changed my attitude to an author, a period, or even literature in general? By "changed," I didn't mean "unconsciously shaped," in the way that my childhood immersion in nineteenth-century literature permanently formed my literary tastes. Moreover, I also ruled college courses out of the mix; the courses I took in Romantic and Victorian poetry during my sophomore year certainly altered my attitude to poetry, but in those cases the cumulative effect of a quarter's reading won out over individual works.
After chewing on this question for a while, I came up with three instances:
1. Alfred Bester, "Fondly Fahrenheit." I first read this short story at the age of eight, which was too young, strictly speaking. But even though I couldn't have explained how Bester was playing with the conventions of POV, I still realized for the first time that an author could play games with his narrative voices--that, in fact, a narrator might be unreliable (a term I wouldn't have known then, either).
2. Charles Dickens, Bleak House. There are many ways of experiencing a novel's greatness; this was the first time that I felt both astonished and humbled by an author's power. Bleak House also managed to convert me to Dickens, whose grotesques I had always found rather off-putting.
3. Sir Walter Scott, The Bride of Lammermoor. One of those moments when you realize that an author's reputation really does deserve to be dusted off and polished up. The novel also cured my allergy to Gothic fiction--which I must confess that I had not enjoyed in its Ann Radcliffe incarnation.