There was a man born blind, and he said: “I do not believe in the of light and appearance. There are no colours, bright or somber. There is no , no , no stars. No 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 you see colours.”

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