“These six physicians were heroes of the medieval era, both to the Christian West and the Muslim East. Dante places them amongst the classical poets in the outer circle of hell, which was set aside for virtuous pagans–a place of green fields overlooked by a castle with seven gates for the seven virtues.”
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.