《淮南子·俶真训》
镜子明亮，尘埃就不会玷污它，精神心志纯白清静，嗜欲也就难以搅乱它。
夫鉴明者，尘垢弗能藐；神清者，嗜欲弗能乱。
If a mirror is bright, dust will not defile it. If the spirit heart and mind are pure and clear, desires will find it difficult to disturb them.