Hsien-tzu ("Clam"; Japanese: Kensu) and Chu-t'ou ("Pig's Head"; Japanese: Choto) are two typical Ch'an characters. Although they were originally in no way related or associated, they are often depicted on scrolls that form a pair. Their association is probably due to the non-vegetarian habits that they share,which set them apart from the regular Buddhist clergy to whom such habits were anathema.When he went to Master Tao of Wen-shu, who was to become his teacher, the Master asked him: "What did you see when you were about to slaughter that pig? What made you shave your head and depart on a pilgrimage?" Ssu-yeh thereupon made a gesture as if he were whetting his knife.
Hsien-tzu is supposed to have been a disciple of Tung-shan Liang-chieh (807-869). He was not a Ch'an monk in the usual sense, however. Dressed in the same rags in summer and winter, he roamed the riverside with his fishing net in search of shrimps and clams, which formed his staple diet. At night he would sleep among the offerings of paper money made to the White Horse Shrine on Eastern Mountain.
It was said that he attained Enlightenment while catching shrimp.
The identity of Hsien-tzu's companion Chu-t'ou is rather unclear. His name means pig's head and he is usually shown eating a pig's head or holding one in his hands. He is usually said to represent a certain Chih Meng-hsu who was fond of eating pig and was therefore called "Pig's Head." There is nothing in Chih's biography, however, that could justify his inclusion in the Ch'an pantheon of eccentrics.
There are two other Ch'an stories, which possibly could be relevant to this theme. The first concerns the monk Wen-shu Ssu-yeh who started his career as a butcher. One day, on the point of killing yet another pig, he suddenly realized the error of his ways in a flash of revelation. He quit his trade to become a monk and composed the following gathaon the occasion:
Yesterday the heart of a [bloodthirsty] Yaksa,
Today the face of a Bodhisattva.
Between the Bodhisattva and the Yaksa
There is not a shred of difference.