Duke Mu of Ch'in said to Po Lo: 'You are now advanced in years. Is there any member of your family whom I could employ to look for horses in your stead?' Po Lo replied: 'A good horse can be picked out by its general build and appearance. But the superlative horse — one that raises no dust and leaves no tracks — is something evanescent and fleeting, elusive as thin air. The talent of my sons lies on a lower plane altogether: they can tell a good horse when they see one, but they cannot tell a superlative horse. I have a friend, however, one Chiu-fang Kao, a hawker of fuel and vegetables, who in things appertaining to horses is nowise my inferior. Pray see him.' Duke Mu did so, and subsequently despatched him on the quest for a steed. Three months later, he returned with the news that he had found one. 'It is now in Sha-ch'iu,' he added. 'What kind of a horse is it?' asked the Duke. 'Oh, it is a dun-coloured mare,' was the reply. However, on some one being sent to fetch it, the animal turned out to be a coal-black stallion! Much displeased, the Duke sent for Po Lo. 'That friend of yours,' he said, 'whom I commissioned to look for a horse, has made a nice mess of it. Why, he cannot even distinguish a beast's colour or sex! What on earth can he know about horses?' Po Lo heaved a sigh of satisfaction. 'Has he really got as far as that?' he cried. 'Ah, then he is worth a thousand of me put together. There is no comparison between us. What Kao keeps in view is the spiritual mechanism. In making sure of the essential, he forgets the homely details; intent on the inward qualities, he loses sight of the external. He sees what he wants to see, and not what he does not want to see. He looks at the things he ought to look at, and neglects those that need not be looked at. So clever a judge of horses is Kao, that he has it in him to judge something better than horses.' When the horse arrived, it turned out indeed to be a superlative horse.