I love this article from The Economist (and wish I knew when it was published). Here's a snip:
It does scant justice to the deep nature of a life to suppose that a book can simply "change" it. Literature is not a one-off remedy. And actually it is the reading of books itself, amongst other things, that has helped me appreciate that deep complex nature. Nonetheless, I do remain convinced that life without reading and the personal thinking it provokes would be a greatly diminished thing.
It could be that Shakespeare's use of language gets so far into our brains that he shifts and new-creates pathways--not unlike the establishment of new biological networks using novel combinations of existing elements (genes/proteins in biology: units of phonology, semantics, syntax , and morphology in language). Then indeed we might be able to see something of the ways literature can cause affect or create change, without resorting to being assertively gushy.
Here's a link to the entire story.