There was a born blind, and he said: “I do not believe in the world of and appearance. There are colours, bright or somber. There is sun, moon, stars. one has witnessed these things.”

His friends remonstrated with him, but he clung to his opinion: “What you say that you see,” he objected, “are illusions. If colours existed I should be able to touch them. They have no substance and are not real. Everything real has weight, but I feel no weight where .”

A was called to see the blind man. He mixed four simples, and when he applied them to the of the blind man the grey film melted, and his eyes could see. The Tathagatha is the , the cataract is the illusion . . . and the four simples are the four noble truths.