The unicorn has but one horn in the middle of its forehead. It is the only animal that ventures to attack the elephant; and so sharp is the nail of its foot, that with one blew it can rip the belly of that beast. Hunters can catch the unicorn only by placing a young virgin in its haunts. No sooner does he see the damsel, than he runs towards her, and lies down at her feet, and so suffers himself to be captured by the hunters. The unicorn represents Jesus Christ, who took on Him our nature in the virgin's womb, was betrayed to the Jews, and delivered into the hands of Pontius Pilate. Its one horn signifies the Gospel of Truth.
--Le Bestiaire Divin de Guillaume, Clerc de Normandic--
(Thirteenth Century)