The deification of Laozi is well documented and its timing is instructive. In the Han the historical figure was already becoming legendary; by the second century CE he was Taishang Laojun, a cosmic deity who takes bodily form in successive ages to deliver the teaching to whoever will receive it, and it is in that capacity that he appears to Zhang Daoling on Heming Mountain in 142 to establish the covenant. The doctrine of repeated manifestations produced one of the great polemical texts of Chinese history, the Huahujing, which claimed that Laozi went west through the pass and became the Buddha — an argument the Buddhists fought bitterly and eventually won, with the text ordered destroyed under the Yuan. His image is on the altar of most temples as the third of the Three Pure Ones, white-bearded, sometimes riding the green ox he left China on.