touchstone

As far as I am able to understand, a touchstone is a passage that is particularly enlightening or leads us to the sublime. From talking in class I thought maybe it had to have some relevance to literature (like it had to comment on literature) as well but I don't really see why that would be necessary. In that case one touchstone of mine would be from Elizabeth Barrett Browning's Aurora Leigh where Aurora says,

"All heroes are essential men, and all men possible heroes."

Another one would be from Steinbeck's East of Eden where he says,

"And this I believe: that the free, exploring mind of the individual human is the most valuable thing in the world. And this I would fight for: the freedom of the mind to take any direction it wishes, undirected."

Those are two that I can think of right now, if I think of anymore and can find them I will report back