《太平广记·卷七十四·道术四》
张定独自走了一百多步，有一个道士走得很急。那个道士回头看见了他，就站住对他说： 你这个人可以教啊。 
独行百余步，有一道士行甚急，顾见之，立而言曰： 此可教也。 
Zhang Ding walked alone for more than a hundred steps when he came across a Daoist priest who was walking very quickly. When the priest looked back and  saw him, he stopped and told him, "You are someone who can be taught."