English Original
During the Spring and Autumn period, there was a man in the state of Qin named Sun Yang. He was an expert in judging horses, able to tell their quality at a glance. People called him Bo Le (a celestial figure fabled to be in charge of heavenly steeds) and often sought his appraisal.
One day, Sun Yang encountered an old horse pulling a heavy salt cart. He recognized it as a steed capable of covering a thousand li a day, now worn down by its labor. Moved by its unjust treatment, he shed tears, imagining it galloping on a battlefield instead.
To preserve his knowledge and help others identify fine horses, Sun Yang wrote a book titled The Art of Looking at Horses and Judging Their Worth, illustrated with pictures of various horses.
His son, after reading the book, thought appraising horses was easy. He took the book to search for a fine steed. Finding no match by the pictures alone, he then looked for matching characteristics. He found a toad that seemed to fit the book's description and brought it home, declaring, "Father, I've found a horse that can cover a thousand li a day, only its hoofs are not good enough."
Sun Yang, not knowing whether to laugh or cry, said humorously, "It's a pity this horse is too fond of jumping to pull a cart." He then sighed, "That is just what we call 'looking for a steed with the aid of its picture.'"
Later, this set phrase came to mean handling affairs mechanically by the book, without flexibility. It can also refer to trying to locate something by following a clue.
中文翻译
春秋时期，秦国有一位名叫孙阳的人。他善于相马，一眼就能看出一匹马的好坏。人们称他为伯乐（传说中掌管天马的神仙），并经常请他鉴定和挑选马匹。
一天，孙阳路过一个地方，一匹拉着沉重盐车的老马突然不停地向他嘶鸣。他走近一看，发现这确实是一匹能日行千里的好马，只是年纪稍大。老马艰难地拉着车，孙阳深感它被埋没了，这本该是在战场上驰骋的骏马。他想到此，不禁伤心落泪。
为了让更多人学会相马，使千里马不再被埋没，也为了不让自己的绝技失传，孙阳根据多年经验，写了一本名为《相马经》的书，书中还配有各种马的图片。
孙阳的儿子读了父亲的《相马经》后，以为相马很容易，便拿着书到处去找好马。起初他按图索骥，一无所获。后来，他根据书中描述的特征去寻找，发现一只癞蛤蟆的特征非常符合。于是他高兴地把癞蛤蟆带回家，对父亲说：“父亲，我找到一匹日行千里的好马了，只是蹄子不太像。”
孙阳看着癞蛤蟆，哭笑不得。他知道儿子愚笨，便幽默地说：“可惜这匹马太喜欢跳了，不能拉车。”接着他叹息道：“这就是所谓的‘按图索骥’啊。”
后来，人们便用“按图索骥”这个成语来比喻办事机械、死板，不知变通。有时也比喻依照线索去寻找事物。