The story that a unicorn can only be captured by a virgin, in whose lap it lays its head and sleeps until the hunters come, is not classical. It appears in the Physiologus, a Greek Christian compilation of animal allegories written in Alexandria probably in the second century, which pairs each creature with a doctrinal reading. The unicorn's small size, fierceness and capture by a maiden are read as the incarnation: Christ, whom no power could hold, taken into the womb of the Virgin.
The Physiologus was translated into Latin, Syriac, Armenian, Ethiopic and most European vernaculars and became the basis of the medieval bestiary, which is why the unicorn hunt is one of the most reproduced images in European art. The two great surviving cycles are the Lady and the Unicorn, six tapestries woven in Flanders around 1500 and now at the Musee de Cluny in Paris, which present the five senses and a sixth panel whose meaning is disputed; and the Hunt of the Unicorn, seven tapestries of about the same date now at the Cloisters in New York, which follow the hunt through to the killing and then show the unicorn alive and enclosed in a garden.
Two animals frequently identified with the unicorn are not the same creature. The Chinese qilin is a composite auspicious beast whose appearance signals the arrival or passing of a sage; it may be depicted with one horn or two, and its associations are with benevolence and portent, not with virginity or purity. The Persian and Arabic karkadann is a fierce one-horned beast, ultimately the rhinoceros again, and in some late texts it acquires the maiden-taming motif by borrowing from the West. Treating the three as one animal travelling across Eurasia is a modern conflation.