Chapter 5, Part 4A - Lieh Tzu

Kung-hu of Lu and Ch'i-ying of Chao both fell ill at the same time, and called in the aid of the great Pien-ch'iao.

Pien-ch'iao cured them both, and when they were well again he told them that the malady they had been suffering from was one that attacked the internal organs from without, and for that reason was curable by the application of vegetable and mineral drugs. 'But,' he added, 'each of you is also the victim of a congenital disease, which has grown along with the body itself. Would you like me now to grapple with this?'

They said, 'Yes'; but asked to hear his diagnosis first.

Pien-ch'iao turned to Kung-hu. 'Your mental powers,' he said, 'are strong, but your willpower is weak. Hence, though fruitful in plans, you are lacking in decision. Ch'i-ying's mental powers, on the other hand, are weak, while his will-power is strong. Hence there is want of forethought, and he is placed at a disadvantage by the narrowness of his aim. Now, if I can effect an exchange of hearts between you, the good will be equally balanced in both.'
~ Lionel Giles translation via Terebess Asia Online ~

Go here to read the introductory post to the chapters of the Book of Lieh Tzu.