Wikipedia
Hakuraku
Hakuraku (aka Sun Yang or Po Lo) was a hero in Oriental mythology. Dispatched by the Chinese Emperor with the task of locating the perfect horse, Hakuraku returned with news of a bay mare that he had found. However, when Imperial soldiers were sent to fetch the horse, they found it was a black stallion instead.
The story illustrates the Confucian and Taoist adage that expert knowledge embodies the ability to see past exterior appearances to the true nature of a subject.
The term hakuraku is now used as Japanese slang for a veterinarian.