The Shurangama Sutra, Volume X: Illusory Brightness and False Thinking

Original Text: This very thought of imagining oneself at a height can cause your physical body to truly experience sourness and numbness. Because the arising of mental sensation can move the physical body. What you presently perceive before you—the two phenomena of comfort from favorable conditions that benefit the body and pain from adverse conditions that harm the body—are driven by what is called the "empty brightness," the second delusion.

Explanation: The previous delusional thought of imagining oneself standing on a cliff edge can cause a genuine sensation of sourness and numbness in the soles of your feet. Because the arising of inner sensations can induce changes in the physical body. For example, the occurrence of the two phenomena mentioned earlier makes your mind perceive the sour object and the cliff as present, thereby causing physical changes. The comfortable sensations you now experience when encountering favorable conditions that benefit the body, and the painful feelings when encountering adverse conditions that harm the body—these two phenomena are called the "empty brightness," the second delusion.

This indicates that the skandha of sensation is an empty brightness delusion, which is also an error of delusion, and therefore not real. Clinging to the skandha of sensation leads to the suffering of birth and death within cyclic existence, preventing liberation from afflictions.