> I also would bet a "sacred book" of some sort also worked as a prerequisite What you point out is fascinating, and probably right ... PS. I am wondering if

> I also would bet a "sacred book" of some sort also worked as a prerequisite What you point out is fascinating, and probably right ... PS. I am wondering if "any sufficiently popular" book might not have done the trick, beyond just "sacred" texts - one of the many knightly tales than making the round, for example.-