E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
According to the legends of the Middle Ages, the unicorn could be caught only by placing a virgin in his haunts; upon seeing the virgin, the creature would lose its fierceness and lie quiet at her feet. This is said to be an allegory of Jesus Christ, who willingly became man and entered the Virgins womb, when He was taken by the hunters of blood. The one horn symbolises the great Gospel doctrine that Christ is one with God. (Guillaume, Clerc de Normandic Trouvère.)
The unicorn has the legs of a buck, the tail of a lion, the head and body of a horse, and a single horn in the middle of its forehead. The horn is white at the base, black in the middle, and red at the tip. The body of the unicorn is white, the head red, and eyes blue. The oldest author that describes it is Ctesias (B.C. 400); Aristotle calls it the Wild Ass; Pliny, the Indian Ass; Lobo also describes it in his History of Abyssinia.
Unicorn. James I. substituted a unicorn, one of the supporters of the royal arms of Scotland, for the red dragon of Wales, introduced by Henry VII. Ariosto refers to the arms of Scotland thus:
Yon lion placed two unicorns between
That rampant with a silver sword is seen.
Is for the king of Scotlands banner known.
Unicorn. According to a belief once popular, the unicorn by dipping its horn into a liquid could detect whether or not it contained poison. In the designs for gold and silver plate made for the Emperor Rudolph II. by Ottavio Strada is a cup on which a unicorn stands as if to essay the liquid.
Driving unicorn. Two wheelers and one leader. The leader is the one horn, (Latin, unum cornu, one horn.)