Lao-tzŭ left heavenly purity and honour for earthly pollution and office. It was under the Heaven-blessed kings Wên (文王) and Wu (武王) that he first took service in the state as Treasury keeper and then as Assistant historiographer. This account, however, would make him survive for the more than patriarchal period of five hundred years. He is represented as having several interviews with Confucius who, as Szŭ Ma-chien also relates, compared him to a dragon which in a mysterious and inexplicable manner mounts a cloud and soars into heaven. This, as Rémusat has observed, was intended as a compliment, the dragon being with the Chinese a symbol of what is exalted and not unattended by a mysterious power.[33] On retiring from office Lao-tzŭ proceeded westward intending to pass through the Han-ku-kwan (函谷關) to the Kunlun mountains and other distant places. Yin-hsi (尹喜), however, the keeper of the pass, who had known from the state of the weather that a sage was to come his way, recognised Lao-tzŭ for such and detained him until he had himself learned Tao. The time came, however, when the two worthies had to part. Lao-tzŭ informed Yin-hsi that he would have to leave him and go away on a long wandering through the boundless realms of space. Yin-hsi begged earnestly that he might be allowed to go with him—saying that he was prepared to follow the Great Genius through fire and water above the heavens and beneath the earth. Lao-tzŭ declined the offer, but presented his old friend with five thousand words on Tao and Tê.