Robert Pinsky in Slate:
Mistakes are instructive. In particular, they can become a form of analysis, as, for example, in sports or music, when getting something a little bit wrong leads to improvement in technique or understanding.
Many of us, in the imperfect memorizing of a poem, make mistakes, too—as though we were folk singers or blues artists, but without the traditional flexibility of those forms. Is it “many recognitions dim and faint,” you might ask yourself, or “many recognitions sad and faint”? And, before you can find the authoritative book and check, which one do you prefer? And why?
A dramatic demonstration of this principle came to me on a hike in the mountains years ago.
More here.