To “affect” is a tricky thing. I agree with the first part of Mr. Stevenson’s quote, because yes: precision is crucial. There’s so much wrapped up in that statement. The literary writer must chose exact language which will set the tone and voice of the piece.
However, just because the work means something particularly to me, it doesn’t mean that the reader is obligated to feel the same. Rather, I think my job is done when I’ve made the reader feel anything at all. Good literature prods at one’s soul, and blends into memories, experiences and ambitions. It can (and should) make you look at life differently (from the slightest bit to the largest epiphany), but it’s a private, perhaps religious experience between the reader and the book. I am the conductor, delivering my story as an electrical cord facilitates light.
As a matter of fact, my favorite Broadway musical is Jekyll & Hyde. I must’ve seen it thirty times. (I realize it’s not in Stevenson’s words, but it is his creation.) I felt differently about it every time, depending on my frame of mind and what the play stirred inside.
Another example is The Catcher in the Rye. Reading it as an adolescent, I felt way differently than as an adult.
And when I read some of my past work, I feel differently than when I wrote it. What an experience it is, to be affected by one’s own writing years later!
So, it’s my contention that an author absolutely cannot induce a reader to be affected in a specific way. Nor should we want to. It would be like trying to find the cure for madness: we might create a monster instead.
There’s a fine line between lunatic and novelist.