Bo Le was a famous expert in the physiognomy of horses in ancient China. His book On the Physiognomy of Horses was a classic piece of work on that subject.

Bo Le had a son who wanted to learn his father's special skill and knowledge. He read the book On the Physiognomy of Horses over and over again. Whenever he went out, he would carry the book with him, and as soon as he saw a horse, he would take out the book, and compare the horse with the drawings of various horses in the book one by one.

One day, he finally found a horse which looked similar to the drawing in the book. He led it home to his father, but it turned out to be an inferior horse of fiery temperament, and not a good steed which could gallop 1, 000 li a day.  Bo Le said to his son: "If you look for a steed with the aid of drawings, how can you find a really fine one?"

伯乐是中国古代有名的相马专家。《相马经》是他的一本相马的专著。

伯乐有个儿子很想把父亲的技能继承下来。他反复阅读《相马经》，出去相马时也带在身边，一看到马，就把书拿出来，按照书上绘画的各种马的图样，一一加以对照。

一天，他终于找到了一匹马，看来跟书上绘着的一样，牵回家给父亲一看，却是一匹性子很凶悍的劣马，而不是日行千里的好马。伯乐对儿子说：“像你这样照着图样找良马的方法，怎么能找得到真正的好马呢?”