Here's an interesting read: http://www.acton.org/publicat/randl/article.php?id=422 My highlight >> "Jefferson’s “wall,” according to conventional wisdom, represents a universal principle on the prudential and constitutional relationship between religion and the civil state. To the contrary, this “wall” had less to do with the separation between religion and all civil government than with the separation between federal and state governments on matters pertaining to religion. The “wall of separation” was a metaphoric construction of the U.S. Constitution’s First Amendment, which Jefferson said imposed its restrictions on the federal government only. In other words, the “wall” Jefferson constructed separated the federal regime on one side and state governments and religious authorities on the other...."