Deities wearing snakes as their emblems often bear them in the shape of the crescent moon, symbol of growth and fertility.  But through the moon the snake is also associated with night, death, and menstrual blood.

The crescent moon also suggests horns. Horns derived additional symbolic power from their connection with the phallus and with the procreative powers of bull animals.  Horns are also identified with the rays of the sun.  The sign of horns (such as the upturned horseshoe) brings good luck, fertility, and power.

The Devil's horns therefore symbolize his princely power, but they also carry a powerful negative connotation.  Horns bring to mind the danger of wild beasts and the bull that gores; they suggest the mysterious, frightening otherness of animals; and their association with the moon recalls not only fertility but also night, darkness, and death.


(The Prince of Darkness - Jeffrey Burton Russel)