Title: Describing the Undefinable: New Books on Magic and Old Problems of Definition<i>Magic and Magicians in the Greco-Roman World</i>. By Matthew Dickie. London: Routledge, 2001. Pp. viii+380. $90.00.<i>Magic in the Roman World: Pagans, Jews and Christians</i>. By Naomi Janowitz. London: Routledge, 2001. Pp. xiii+145. $24.95.<i>Greek and Roman Necromancy</i>. By Daniel Ogden. Princeton, N.J.: Princeton University Press, 2001. Pp. xiii+ 313. $47.50.