Aryeh Cohen on the Eruv
Aryeh Cohen has a nice article about the meaning of the shabbut eruv and a story illustrating its meaning.
The brilliance of the Rabbinic Shabbat as an urban phenomenon is that it allows Jews to mentally map exclusively Jewish geography while simultaneously sharing that geography with all manner of non-Jews. The eruv, further, allows Jews to symbolically map that territory to the extent that its status is changed from inside to outside—but this is only obvious to those in the community. Therefore, in Los Angeles, when I walk down my street chatting with my non-Jewish neighbor, I am walking in Shabbat while he is not.
See here for the full article.