On one occasion the Venerable Ānanda and the Venerable Kāmabhū were dwelling at Kosambī in Ghosita’s Park. Then, in the evening, the Venerable Kāmabhū emerged from seclusion and approached the Venerable Ānanda. He exchanged greetings with the Venerable Ānanda and, when they had concluded their greetings and cordial talk, he sat down to one side and said to him:
“How is it, friend Ānanda, is the eye the fetter of forms or are forms the fetter of the eye?… Is the mind the fetter of mental phenomena or are mental phenomena the fetter of the mind?”
“Friend Kāmabhū, the eye is not the fetter of forms nor are forms the fetter of the eye … The mind is not the fetter of mental phenomena nor are mental phenomena the fetter of the mind, but rather the desire and lust that arise there in dependence on both: that is the fetter there. sn.iv.166
“Suppose, friend, a black ox and a white ox were yoked together by a single harness or yoke. Would one be speaking rightly if one were to say: ‘The black ox is the fetter of the white ox; the white ox is the fetter of the black ox’?”
“No, friend. The black ox is not the fetter of the white ox nor is the white ox the fetter of the black ox, but rather the single harness or yoke by which the two are yoked together: that is the fetter there.”
“So too, friend, the eye is not the fetter of forms … nor are mental phenomena the fetter of the mind, but rather the desire and lust that arise there in dependence on both: that is the fetter there.”