The pupil of a "bamboo acrobat" (candālavamsika) (See KS.v.148, n.3) of long ago. His master called to him one day and asked him to climb the bamboo and to stand on his shoulder. Then the master suggested that they should watch and look after each other during their performances. But Medakathalikā said that each should look after himself, which would be the better way.
The Commentary (SA.iii.182) adds that, in this performance, the end of the pole rests on the forehead or throat. The man who thus holds it must watch the balance closely and not attend to the man at the end of the pole.
The Buddha related this story at Desakā, in the Sumbha country, to the monks, and said that, in the same way, each monk should look after himself; by guarding oneself, one guards another; this is done by the cultivation of the four satipatthānas (S.v.168f).
The name Medakathalikā, though feminine in inflection, is used for a male (SA.iii.181).