Samyukta Āgama (2) 21
A forest spirit admonishes a monk
The simile of the ulcer
At that time a certain monk put on his robes, took his begging-bowl and entered the town to beg for food. When he had eaten and returned, he washed his feet, took up his sitting mat and went into the Forest of Regained Sight. Having spread out grass beneath a tree he sat down to meditate. But evil thoughts arose in his mind, desire for the five sensual pleasures. The spirit of the Forest of Regained Sight knew the monks thoughts and saw that they were impure. “In this forest one should not have evil inclinations,” the spirit thought, “I will wake him up.” And he said: “Monk, monk, why do you have an ulcer?” The monk answered: “I will bandage it.” The forest spirit spoke again: “Your ulcer is as big as a pot. How will you bandage it?” The monk answered: “I will bandage my ulcer with right thought.” The forest spirit praised him, saying: “Very good, very good! This monk knows well how to bandage his ulcer, how truly to bandage his ulcer.” The Buddha, with his divine hearing, heard the exchange between the forest spirit and the monk.