In Irish mythology, the goddess Medb is said to always have a bird perched on one shoulder and a squirrel on the other, serving as her messengers to the sky and the earth respectively. In Europe during the Middle Ages, squirrels were sometimes used in bestiaries as symbols of greed and avarice on account of their storing of nuts, but, in the nineteenth century, British natural history books often praised them as thrifty for this same reason. A myth told by the Ainu people of Japan holds that squirrels are the discarded sandals of the ancestral deity Aioina, possibly because squirrels move in spurts like footsteps. The "Kalevala", a Finnish epic poem collected in the nineteenth century but rooted in much older oral tradition, contains references to squirrels, including mention of a white squirrel being born of a virgin.